--- a/env/lib/python3.7/site-packages/yaml/scanner.py	Thu May 14 16:47:39 2020 -0400
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1435 +0,0 @@
-
-# Scanner produces tokens of the following types:
-# STREAM-START
-# STREAM-END
-# DIRECTIVE(name, value)
-# DOCUMENT-START
-# DOCUMENT-END
-# BLOCK-SEQUENCE-START
-# BLOCK-MAPPING-START
-# BLOCK-END
-# FLOW-SEQUENCE-START
-# FLOW-MAPPING-START
-# FLOW-SEQUENCE-END
-# FLOW-MAPPING-END
-# BLOCK-ENTRY
-# FLOW-ENTRY
-# KEY
-# VALUE
-# ALIAS(value)
-# ANCHOR(value)
-# TAG(value)
-# SCALAR(value, plain, style)
-#
-# Read comments in the Scanner code for more details.
-#
-
-__all__ = ['Scanner', 'ScannerError']
-
-from .error import MarkedYAMLError
-from .tokens import *
-
-class ScannerError(MarkedYAMLError):
-    pass
-
-class SimpleKey:
-    # See below simple keys treatment.
-
-    def __init__(self, token_number, required, index, line, column, mark):
-        self.token_number = token_number
-        self.required = required
-        self.index = index
-        self.line = line
-        self.column = column
-        self.mark = mark
-
-class Scanner:
-
-    def __init__(self):
-        """Initialize the scanner."""
-        # It is assumed that Scanner and Reader will have a common descendant.
-        # Reader do the dirty work of checking for BOM and converting the
-        # input data to Unicode. It also adds NUL to the end.
-        #
-        # Reader supports the following methods
-        #   self.peek(i=0)       # peek the next i-th character
-        #   self.prefix(l=1)     # peek the next l characters
-        #   self.forward(l=1)    # read the next l characters and move the pointer.
-
-        # Had we reached the end of the stream?
-        self.done = False
-
-        # The number of unclosed '{' and '['. `flow_level == 0` means block
-        # context.
-        self.flow_level = 0
-
-        # List of processed tokens that are not yet emitted.
-        self.tokens = []
-
-        # Add the STREAM-START token.
-        self.fetch_stream_start()
-
-        # Number of tokens that were emitted through the `get_token` method.
-        self.tokens_taken = 0
-
-        # The current indentation level.
-        self.indent = -1
-
-        # Past indentation levels.
-        self.indents = []
-
-        # Variables related to simple keys treatment.
-
-        # A simple key is a key that is not denoted by the '?' indicator.
-        # Example of simple keys:
-        #   ---
-        #   block simple key: value
-        #   ? not a simple key:
-        #   : { flow simple key: value }
-        # We emit the KEY token before all keys, so when we find a potential
-        # simple key, we try to locate the corresponding ':' indicator.
-        # Simple keys should be limited to a single line and 1024 characters.
-
-        # Can a simple key start at the current position? A simple key may
-        # start:
-        # - at the beginning of the line, not counting indentation spaces
-        #       (in block context),
-        # - after '{', '[', ',' (in the flow context),
-        # - after '?', ':', '-' (in the block context).
-        # In the block context, this flag also signifies if a block collection
-        # may start at the current position.
-        self.allow_simple_key = True
-
-        # Keep track of possible simple keys. This is a dictionary. The key
-        # is `flow_level`; there can be no more that one possible simple key
-        # for each level. The value is a SimpleKey record:
-        #   (token_number, required, index, line, column, mark)
-        # A simple key may start with ALIAS, ANCHOR, TAG, SCALAR(flow),
-        # '[', or '{' tokens.
-        self.possible_simple_keys = {}
-
-    # Public methods.
-
-    def check_token(self, *choices):
-        # Check if the next token is one of the given types.
-        while self.need_more_tokens():
-            self.fetch_more_tokens()
-        if self.tokens:
-            if not choices:
-                return True
-            for choice in choices:
-                if isinstance(self.tokens[0], choice):
-                    return True
-        return False
-
-    def peek_token(self):
-        # Return the next token, but do not delete if from the queue.
-        # Return None if no more tokens.
-        while self.need_more_tokens():
-            self.fetch_more_tokens()
-        if self.tokens:
-            return self.tokens[0]
-        else:
-            return None
-
-    def get_token(self):
-        # Return the next token.
-        while self.need_more_tokens():
-            self.fetch_more_tokens()
-        if self.tokens:
-            self.tokens_taken += 1
-            return self.tokens.pop(0)
-
-    # Private methods.
-
-    def need_more_tokens(self):
-        if self.done:
-            return False
-        if not self.tokens:
-            return True
-        # The current token may be a potential simple key, so we
-        # need to look further.
-        self.stale_possible_simple_keys()
-        if self.next_possible_simple_key() == self.tokens_taken:
-            return True
-
-    def fetch_more_tokens(self):
-
-        # Eat whitespaces and comments until we reach the next token.
-        self.scan_to_next_token()
-
-        # Remove obsolete possible simple keys.
-        self.stale_possible_simple_keys()
-
-        # Compare the current indentation and column. It may add some tokens
-        # and decrease the current indentation level.
-        self.unwind_indent(self.column)
-
-        # Peek the next character.
-        ch = self.peek()
-
-        # Is it the end of stream?
-        if ch == '\0':
-            return self.fetch_stream_end()
-
-        # Is it a directive?
-        if ch == '%' and self.check_directive():
-            return self.fetch_directive()
-
-        # Is it the document start?
-        if ch == '-' and self.check_document_start():
-            return self.fetch_document_start()
-
-        # Is it the document end?
-        if ch == '.' and self.check_document_end():
-            return self.fetch_document_end()
-
-        # TODO: support for BOM within a stream.
-        #if ch == '\uFEFF':
-        #    return self.fetch_bom()    <-- issue BOMToken
-
-        # Note: the order of the following checks is NOT significant.
-
-        # Is it the flow sequence start indicator?
-        if ch == '[':
-            return self.fetch_flow_sequence_start()
-
-        # Is it the flow mapping start indicator?
-        if ch == '{':
-            return self.fetch_flow_mapping_start()
-
-        # Is it the flow sequence end indicator?
-        if ch == ']':
-            return self.fetch_flow_sequence_end()
-
-        # Is it the flow mapping end indicator?
-        if ch == '}':
-            return self.fetch_flow_mapping_end()
-
-        # Is it the flow entry indicator?
-        if ch == ',':
-            return self.fetch_flow_entry()
-
-        # Is it the block entry indicator?
-        if ch == '-' and self.check_block_entry():
-            return self.fetch_block_entry()
-
-        # Is it the key indicator?
-        if ch == '?' and self.check_key():
-            return self.fetch_key()
-
-        # Is it the value indicator?
-        if ch == ':' and self.check_value():
-            return self.fetch_value()
-
-        # Is it an alias?
-        if ch == '*':
-            return self.fetch_alias()
-
-        # Is it an anchor?
-        if ch == '&':
-            return self.fetch_anchor()
-
-        # Is it a tag?
-        if ch == '!':
-            return self.fetch_tag()
-
-        # Is it a literal scalar?
-        if ch == '|' and not self.flow_level:
-            return self.fetch_literal()
-
-        # Is it a folded scalar?
-        if ch == '>' and not self.flow_level:
-            return self.fetch_folded()
-
-        # Is it a single quoted scalar?
-        if ch == '\'':
-            return self.fetch_single()
-
-        # Is it a double quoted scalar?
-        if ch == '\"':
-            return self.fetch_double()
-
-        # It must be a plain scalar then.
-        if self.check_plain():
-            return self.fetch_plain()
-
-        # No? It's an error. Let's produce a nice error message.
-        raise ScannerError("while scanning for the next token", None,
-                "found character %r that cannot start any token" % ch,
-                self.get_mark())
-
-    # Simple keys treatment.
-
-    def next_possible_simple_key(self):
-        # Return the number of the nearest possible simple key. Actually we
-        # don't need to loop through the whole dictionary. We may replace it
-        # with the following code:
-        #   if not self.possible_simple_keys:
-        #       return None
-        #   return self.possible_simple_keys[
-        #           min(self.possible_simple_keys.keys())].token_number
-        min_token_number = None
-        for level in self.possible_simple_keys:
-            key = self.possible_simple_keys[level]
-            if min_token_number is None or key.token_number < min_token_number:
-                min_token_number = key.token_number
-        return min_token_number
-
-    def stale_possible_simple_keys(self):
-        # Remove entries that are no longer possible simple keys. According to
-        # the YAML specification, simple keys
-        # - should be limited to a single line,
-        # - should be no longer than 1024 characters.
-        # Disabling this procedure will allow simple keys of any length and
-        # height (may cause problems if indentation is broken though).
-        for level in list(self.possible_simple_keys):
-            key = self.possible_simple_keys[level]
-            if key.line != self.line  \
-                    or self.index-key.index > 1024:
-                if key.required:
-                    raise ScannerError("while scanning a simple key", key.mark,
-                            "could not find expected ':'", self.get_mark())
-                del self.possible_simple_keys[level]
-
-    def save_possible_simple_key(self):
-        # The next token may start a simple key. We check if it's possible
-        # and save its position. This function is called for
-        #   ALIAS, ANCHOR, TAG, SCALAR(flow), '[', and '{'.
-
-        # Check if a simple key is required at the current position.
-        required = not self.flow_level and self.indent == self.column
-
-        # The next token might be a simple key. Let's save it's number and
-        # position.
-        if self.allow_simple_key:
-            self.remove_possible_simple_key()
-            token_number = self.tokens_taken+len(self.tokens)
-            key = SimpleKey(token_number, required,
-                    self.index, self.line, self.column, self.get_mark())
-            self.possible_simple_keys[self.flow_level] = key
-
-    def remove_possible_simple_key(self):
-        # Remove the saved possible key position at the current flow level.
-        if self.flow_level in self.possible_simple_keys:
-            key = self.possible_simple_keys[self.flow_level]
-            
-            if key.required:
-                raise ScannerError("while scanning a simple key", key.mark,
-                        "could not find expected ':'", self.get_mark())
-
-            del self.possible_simple_keys[self.flow_level]
-
-    # Indentation functions.
-
-    def unwind_indent(self, column):
-
-        ## In flow context, tokens should respect indentation.
-        ## Actually the condition should be `self.indent >= column` according to
-        ## the spec. But this condition will prohibit intuitively correct
-        ## constructions such as
-        ## key : {
-        ## }
-        #if self.flow_level and self.indent > column:
-        #    raise ScannerError(None, None,
-        #            "invalid indentation or unclosed '[' or '{'",
-        #            self.get_mark())
-
-        # In the flow context, indentation is ignored. We make the scanner less
-        # restrictive then specification requires.
-        if self.flow_level:
-            return
-
-        # In block context, we may need to issue the BLOCK-END tokens.
-        while self.indent > column:
-            mark = self.get_mark()
-            self.indent = self.indents.pop()
-            self.tokens.append(BlockEndToken(mark, mark))
-
-    def add_indent(self, column):
-        # Check if we need to increase indentation.
-        if self.indent < column:
-            self.indents.append(self.indent)
-            self.indent = column
-            return True
-        return False
-
-    # Fetchers.
-
-    def fetch_stream_start(self):
-        # We always add STREAM-START as the first token and STREAM-END as the
-        # last token.
-
-        # Read the token.
-        mark = self.get_mark()
-        
-        # Add STREAM-START.
-        self.tokens.append(StreamStartToken(mark, mark,
-            encoding=self.encoding))
-        
-
-    def fetch_stream_end(self):
-
-        # Set the current indentation to -1.
-        self.unwind_indent(-1)
-
-        # Reset simple keys.
-        self.remove_possible_simple_key()
-        self.allow_simple_key = False
-        self.possible_simple_keys = {}
-
-        # Read the token.
-        mark = self.get_mark()
-        
-        # Add STREAM-END.
-        self.tokens.append(StreamEndToken(mark, mark))
-
-        # The steam is finished.
-        self.done = True
-
-    def fetch_directive(self):
-        
-        # Set the current indentation to -1.
-        self.unwind_indent(-1)
-
-        # Reset simple keys.
-        self.remove_possible_simple_key()
-        self.allow_simple_key = False
-
-        # Scan and add DIRECTIVE.
-        self.tokens.append(self.scan_directive())
-
-    def fetch_document_start(self):
-        self.fetch_document_indicator(DocumentStartToken)
-
-    def fetch_document_end(self):
-        self.fetch_document_indicator(DocumentEndToken)
-
-    def fetch_document_indicator(self, TokenClass):
-
-        # Set the current indentation to -1.
-        self.unwind_indent(-1)
-
-        # Reset simple keys. Note that there could not be a block collection
-        # after '---'.
-        self.remove_possible_simple_key()
-        self.allow_simple_key = False
-
-        # Add DOCUMENT-START or DOCUMENT-END.
-        start_mark = self.get_mark()
-        self.forward(3)
-        end_mark = self.get_mark()
-        self.tokens.append(TokenClass(start_mark, end_mark))
-
-    def fetch_flow_sequence_start(self):
-        self.fetch_flow_collection_start(FlowSequenceStartToken)
-
-    def fetch_flow_mapping_start(self):
-        self.fetch_flow_collection_start(FlowMappingStartToken)
-
-    def fetch_flow_collection_start(self, TokenClass):
-
-        # '[' and '{' may start a simple key.
-        self.save_possible_simple_key()
-
-        # Increase the flow level.
-        self.flow_level += 1
-
-        # Simple keys are allowed after '[' and '{'.
-        self.allow_simple_key = True
-
-        # Add FLOW-SEQUENCE-START or FLOW-MAPPING-START.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(TokenClass(start_mark, end_mark))
-
-    def fetch_flow_sequence_end(self):
-        self.fetch_flow_collection_end(FlowSequenceEndToken)
-
-    def fetch_flow_mapping_end(self):
-        self.fetch_flow_collection_end(FlowMappingEndToken)
-
-    def fetch_flow_collection_end(self, TokenClass):
-
-        # Reset possible simple key on the current level.
-        self.remove_possible_simple_key()
-
-        # Decrease the flow level.
-        self.flow_level -= 1
-
-        # No simple keys after ']' or '}'.
-        self.allow_simple_key = False
-
-        # Add FLOW-SEQUENCE-END or FLOW-MAPPING-END.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(TokenClass(start_mark, end_mark))
-
-    def fetch_flow_entry(self):
-
-        # Simple keys are allowed after ','.
-        self.allow_simple_key = True
-
-        # Reset possible simple key on the current level.
-        self.remove_possible_simple_key()
-
-        # Add FLOW-ENTRY.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(FlowEntryToken(start_mark, end_mark))
-
-    def fetch_block_entry(self):
-
-        # Block context needs additional checks.
-        if not self.flow_level:
-
-            # Are we allowed to start a new entry?
-            if not self.allow_simple_key:
-                raise ScannerError(None, None,
-                        "sequence entries are not allowed here",
-                        self.get_mark())
-
-            # We may need to add BLOCK-SEQUENCE-START.
-            if self.add_indent(self.column):
-                mark = self.get_mark()
-                self.tokens.append(BlockSequenceStartToken(mark, mark))
-
-        # It's an error for the block entry to occur in the flow context,
-        # but we let the parser detect this.
-        else:
-            pass
-
-        # Simple keys are allowed after '-'.
-        self.allow_simple_key = True
-
-        # Reset possible simple key on the current level.
-        self.remove_possible_simple_key()
-
-        # Add BLOCK-ENTRY.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(BlockEntryToken(start_mark, end_mark))
-
-    def fetch_key(self):
-        
-        # Block context needs additional checks.
-        if not self.flow_level:
-
-            # Are we allowed to start a key (not necessary a simple)?
-            if not self.allow_simple_key:
-                raise ScannerError(None, None,
-                        "mapping keys are not allowed here",
-                        self.get_mark())
-
-            # We may need to add BLOCK-MAPPING-START.
-            if self.add_indent(self.column):
-                mark = self.get_mark()
-                self.tokens.append(BlockMappingStartToken(mark, mark))
-
-        # Simple keys are allowed after '?' in the block context.
-        self.allow_simple_key = not self.flow_level
-
-        # Reset possible simple key on the current level.
-        self.remove_possible_simple_key()
-
-        # Add KEY.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(KeyToken(start_mark, end_mark))
-
-    def fetch_value(self):
-
-        # Do we determine a simple key?
-        if self.flow_level in self.possible_simple_keys:
-
-            # Add KEY.
-            key = self.possible_simple_keys[self.flow_level]
-            del self.possible_simple_keys[self.flow_level]
-            self.tokens.insert(key.token_number-self.tokens_taken,
-                    KeyToken(key.mark, key.mark))
-
-            # If this key starts a new block mapping, we need to add
-            # BLOCK-MAPPING-START.
-            if not self.flow_level:
-                if self.add_indent(key.column):
-                    self.tokens.insert(key.token_number-self.tokens_taken,
-                            BlockMappingStartToken(key.mark, key.mark))
-
-            # There cannot be two simple keys one after another.
-            self.allow_simple_key = False
-
-        # It must be a part of a complex key.
-        else:
-            
-            # Block context needs additional checks.
-            # (Do we really need them? They will be caught by the parser
-            # anyway.)
-            if not self.flow_level:
-
-                # We are allowed to start a complex value if and only if
-                # we can start a simple key.
-                if not self.allow_simple_key:
-                    raise ScannerError(None, None,
-                            "mapping values are not allowed here",
-                            self.get_mark())
-
-            # If this value starts a new block mapping, we need to add
-            # BLOCK-MAPPING-START.  It will be detected as an error later by
-            # the parser.
-            if not self.flow_level:
-                if self.add_indent(self.column):
-                    mark = self.get_mark()
-                    self.tokens.append(BlockMappingStartToken(mark, mark))
-
-            # Simple keys are allowed after ':' in the block context.
-            self.allow_simple_key = not self.flow_level
-
-            # Reset possible simple key on the current level.
-            self.remove_possible_simple_key()
-
-        # Add VALUE.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(ValueToken(start_mark, end_mark))
-
-    def fetch_alias(self):
-
-        # ALIAS could be a simple key.
-        self.save_possible_simple_key()
-
-        # No simple keys after ALIAS.
-        self.allow_simple_key = False
-
-        # Scan and add ALIAS.
-        self.tokens.append(self.scan_anchor(AliasToken))
-
-    def fetch_anchor(self):
-
-        # ANCHOR could start a simple key.
-        self.save_possible_simple_key()
-
-        # No simple keys after ANCHOR.
-        self.allow_simple_key = False
-
-        # Scan and add ANCHOR.
-        self.tokens.append(self.scan_anchor(AnchorToken))
-
-    def fetch_tag(self):
-
-        # TAG could start a simple key.
-        self.save_possible_simple_key()
-
-        # No simple keys after TAG.
-        self.allow_simple_key = False
-
-        # Scan and add TAG.
-        self.tokens.append(self.scan_tag())
-
-    def fetch_literal(self):
-        self.fetch_block_scalar(style='|')
-
-    def fetch_folded(self):
-        self.fetch_block_scalar(style='>')
-
-    def fetch_block_scalar(self, style):
-
-        # A simple key may follow a block scalar.
-        self.allow_simple_key = True
-
-        # Reset possible simple key on the current level.
-        self.remove_possible_simple_key()
-
-        # Scan and add SCALAR.
-        self.tokens.append(self.scan_block_scalar(style))
-
-    def fetch_single(self):
-        self.fetch_flow_scalar(style='\'')
-
-    def fetch_double(self):
-        self.fetch_flow_scalar(style='"')
-
-    def fetch_flow_scalar(self, style):
-
-        # A flow scalar could be a simple key.
-        self.save_possible_simple_key()
-
-        # No simple keys after flow scalars.
-        self.allow_simple_key = False
-
-        # Scan and add SCALAR.
-        self.tokens.append(self.scan_flow_scalar(style))
-
-    def fetch_plain(self):
-
-        # A plain scalar could be a simple key.
-        self.save_possible_simple_key()
-
-        # No simple keys after plain scalars. But note that `scan_plain` will
-        # change this flag if the scan is finished at the beginning of the
-        # line.
-        self.allow_simple_key = False
-
-        # Scan and add SCALAR. May change `allow_simple_key`.
-        self.tokens.append(self.scan_plain())
-
-    # Checkers.
-
-    def check_directive(self):
-
-        # DIRECTIVE:        ^ '%' ...
-        # The '%' indicator is already checked.
-        if self.column == 0:
-            return True
-
-    def check_document_start(self):
-
-        # DOCUMENT-START:   ^ '---' (' '|'\n')
-        if self.column == 0:
-            if self.prefix(3) == '---'  \
-                    and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
-                return True
-
-    def check_document_end(self):
-
-        # DOCUMENT-END:     ^ '...' (' '|'\n')
-        if self.column == 0:
-            if self.prefix(3) == '...'  \
-                    and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
-                return True
-
-    def check_block_entry(self):
-
-        # BLOCK-ENTRY:      '-' (' '|'\n')
-        return self.peek(1) in '\0 \t\r\n\x85\u2028\u2029'
-
-    def check_key(self):
-
-        # KEY(flow context):    '?'
-        if self.flow_level:
-            return True
-
-        # KEY(block context):   '?' (' '|'\n')
-        else:
-            return self.peek(1) in '\0 \t\r\n\x85\u2028\u2029'
-
-    def check_value(self):
-
-        # VALUE(flow context):  ':'
-        if self.flow_level:
-            return True
-
-        # VALUE(block context): ':' (' '|'\n')
-        else:
-            return self.peek(1) in '\0 \t\r\n\x85\u2028\u2029'
-
-    def check_plain(self):
-
-        # A plain scalar may start with any non-space character except:
-        #   '-', '?', ':', ',', '[', ']', '{', '}',
-        #   '#', '&', '*', '!', '|', '>', '\'', '\"',
-        #   '%', '@', '`'.
-        #
-        # It may also start with
-        #   '-', '?', ':'
-        # if it is followed by a non-space character.
-        #
-        # Note that we limit the last rule to the block context (except the
-        # '-' character) because we want the flow context to be space
-        # independent.
-        ch = self.peek()
-        return ch not in '\0 \t\r\n\x85\u2028\u2029-?:,[]{}#&*!|>\'\"%@`'  \
-                or (self.peek(1) not in '\0 \t\r\n\x85\u2028\u2029'
-                        and (ch == '-' or (not self.flow_level and ch in '?:')))
-
-    # Scanners.
-
-    def scan_to_next_token(self):
-        # We ignore spaces, line breaks and comments.
-        # If we find a line break in the block context, we set the flag
-        # `allow_simple_key` on.
-        # The byte order mark is stripped if it's the first character in the
-        # stream. We do not yet support BOM inside the stream as the
-        # specification requires. Any such mark will be considered as a part
-        # of the document.
-        #
-        # TODO: We need to make tab handling rules more sane. A good rule is
-        #   Tabs cannot precede tokens
-        #   BLOCK-SEQUENCE-START, BLOCK-MAPPING-START, BLOCK-END,
-        #   KEY(block), VALUE(block), BLOCK-ENTRY
-        # So the checking code is
-        #   if <TAB>:
-        #       self.allow_simple_keys = False
-        # We also need to add the check for `allow_simple_keys == True` to
-        # `unwind_indent` before issuing BLOCK-END.
-        # Scanners for block, flow, and plain scalars need to be modified.
-
-        if self.index == 0 and self.peek() == '\uFEFF':
-            self.forward()
-        found = False
-        while not found:
-            while self.peek() == ' ':
-                self.forward()
-            if self.peek() == '#':
-                while self.peek() not in '\0\r\n\x85\u2028\u2029':
-                    self.forward()
-            if self.scan_line_break():
-                if not self.flow_level:
-                    self.allow_simple_key = True
-            else:
-                found = True
-
-    def scan_directive(self):
-        # See the specification for details.
-        start_mark = self.get_mark()
-        self.forward()
-        name = self.scan_directive_name(start_mark)
-        value = None
-        if name == 'YAML':
-            value = self.scan_yaml_directive_value(start_mark)
-            end_mark = self.get_mark()
-        elif name == 'TAG':
-            value = self.scan_tag_directive_value(start_mark)
-            end_mark = self.get_mark()
-        else:
-            end_mark = self.get_mark()
-            while self.peek() not in '\0\r\n\x85\u2028\u2029':
-                self.forward()
-        self.scan_directive_ignored_line(start_mark)
-        return DirectiveToken(name, value, start_mark, end_mark)
-
-    def scan_directive_name(self, start_mark):
-        # See the specification for details.
-        length = 0
-        ch = self.peek(length)
-        while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'  \
-                or ch in '-_':
-            length += 1
-            ch = self.peek(length)
-        if not length:
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected alphabetic or numeric character, but found %r"
-                    % ch, self.get_mark())
-        value = self.prefix(length)
-        self.forward(length)
-        ch = self.peek()
-        if ch not in '\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected alphabetic or numeric character, but found %r"
-                    % ch, self.get_mark())
-        return value
-
-    def scan_yaml_directive_value(self, start_mark):
-        # See the specification for details.
-        while self.peek() == ' ':
-            self.forward()
-        major = self.scan_yaml_directive_number(start_mark)
-        if self.peek() != '.':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected a digit or '.', but found %r" % self.peek(),
-                    self.get_mark())
-        self.forward()
-        minor = self.scan_yaml_directive_number(start_mark)
-        if self.peek() not in '\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected a digit or ' ', but found %r" % self.peek(),
-                    self.get_mark())
-        return (major, minor)
-
-    def scan_yaml_directive_number(self, start_mark):
-        # See the specification for details.
-        ch = self.peek()
-        if not ('0' <= ch <= '9'):
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected a digit, but found %r" % ch, self.get_mark())
-        length = 0
-        while '0' <= self.peek(length) <= '9':
-            length += 1
-        value = int(self.prefix(length))
-        self.forward(length)
-        return value
-
-    def scan_tag_directive_value(self, start_mark):
-        # See the specification for details.
-        while self.peek() == ' ':
-            self.forward()
-        handle = self.scan_tag_directive_handle(start_mark)
-        while self.peek() == ' ':
-            self.forward()
-        prefix = self.scan_tag_directive_prefix(start_mark)
-        return (handle, prefix)
-
-    def scan_tag_directive_handle(self, start_mark):
-        # See the specification for details.
-        value = self.scan_tag_handle('directive', start_mark)
-        ch = self.peek()
-        if ch != ' ':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected ' ', but found %r" % ch, self.get_mark())
-        return value
-
-    def scan_tag_directive_prefix(self, start_mark):
-        # See the specification for details.
-        value = self.scan_tag_uri('directive', start_mark)
-        ch = self.peek()
-        if ch not in '\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected ' ', but found %r" % ch, self.get_mark())
-        return value
-
-    def scan_directive_ignored_line(self, start_mark):
-        # See the specification for details.
-        while self.peek() == ' ':
-            self.forward()
-        if self.peek() == '#':
-            while self.peek() not in '\0\r\n\x85\u2028\u2029':
-                self.forward()
-        ch = self.peek()
-        if ch not in '\0\r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected a comment or a line break, but found %r"
-                        % ch, self.get_mark())
-        self.scan_line_break()
-
-    def scan_anchor(self, TokenClass):
-        # The specification does not restrict characters for anchors and
-        # aliases. This may lead to problems, for instance, the document:
-        #   [ *alias, value ]
-        # can be interpreted in two ways, as
-        #   [ "value" ]
-        # and
-        #   [ *alias , "value" ]
-        # Therefore we restrict aliases to numbers and ASCII letters.
-        start_mark = self.get_mark()
-        indicator = self.peek()
-        if indicator == '*':
-            name = 'alias'
-        else:
-            name = 'anchor'
-        self.forward()
-        length = 0
-        ch = self.peek(length)
-        while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'  \
-                or ch in '-_':
-            length += 1
-            ch = self.peek(length)
-        if not length:
-            raise ScannerError("while scanning an %s" % name, start_mark,
-                    "expected alphabetic or numeric character, but found %r"
-                    % ch, self.get_mark())
-        value = self.prefix(length)
-        self.forward(length)
-        ch = self.peek()
-        if ch not in '\0 \t\r\n\x85\u2028\u2029?:,]}%@`':
-            raise ScannerError("while scanning an %s" % name, start_mark,
-                    "expected alphabetic or numeric character, but found %r"
-                    % ch, self.get_mark())
-        end_mark = self.get_mark()
-        return TokenClass(value, start_mark, end_mark)
-
-    def scan_tag(self):
-        # See the specification for details.
-        start_mark = self.get_mark()
-        ch = self.peek(1)
-        if ch == '<':
-            handle = None
-            self.forward(2)
-            suffix = self.scan_tag_uri('tag', start_mark)
-            if self.peek() != '>':
-                raise ScannerError("while parsing a tag", start_mark,
-                        "expected '>', but found %r" % self.peek(),
-                        self.get_mark())
-            self.forward()
-        elif ch in '\0 \t\r\n\x85\u2028\u2029':
-            handle = None
-            suffix = '!'
-            self.forward()
-        else:
-            length = 1
-            use_handle = False
-            while ch not in '\0 \r\n\x85\u2028\u2029':
-                if ch == '!':
-                    use_handle = True
-                    break
-                length += 1
-                ch = self.peek(length)
-            handle = '!'
-            if use_handle:
-                handle = self.scan_tag_handle('tag', start_mark)
-            else:
-                handle = '!'
-                self.forward()
-            suffix = self.scan_tag_uri('tag', start_mark)
-        ch = self.peek()
-        if ch not in '\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a tag", start_mark,
-                    "expected ' ', but found %r" % ch, self.get_mark())
-        value = (handle, suffix)
-        end_mark = self.get_mark()
-        return TagToken(value, start_mark, end_mark)
-
-    def scan_block_scalar(self, style):
-        # See the specification for details.
-
-        if style == '>':
-            folded = True
-        else:
-            folded = False
-
-        chunks = []
-        start_mark = self.get_mark()
-
-        # Scan the header.
-        self.forward()
-        chomping, increment = self.scan_block_scalar_indicators(start_mark)
-        self.scan_block_scalar_ignored_line(start_mark)
-
-        # Determine the indentation level and go to the first non-empty line.
-        min_indent = self.indent+1
-        if min_indent < 1:
-            min_indent = 1
-        if increment is None:
-            breaks, max_indent, end_mark = self.scan_block_scalar_indentation()
-            indent = max(min_indent, max_indent)
-        else:
-            indent = min_indent+increment-1
-            breaks, end_mark = self.scan_block_scalar_breaks(indent)
-        line_break = ''
-
-        # Scan the inner part of the block scalar.
-        while self.column == indent and self.peek() != '\0':
-            chunks.extend(breaks)
-            leading_non_space = self.peek() not in ' \t'
-            length = 0
-            while self.peek(length) not in '\0\r\n\x85\u2028\u2029':
-                length += 1
-            chunks.append(self.prefix(length))
-            self.forward(length)
-            line_break = self.scan_line_break()
-            breaks, end_mark = self.scan_block_scalar_breaks(indent)
-            if self.column == indent and self.peek() != '\0':
-
-                # Unfortunately, folding rules are ambiguous.
-                #
-                # This is the folding according to the specification:
-                
-                if folded and line_break == '\n'    \
-                        and leading_non_space and self.peek() not in ' \t':
-                    if not breaks:
-                        chunks.append(' ')
-                else:
-                    chunks.append(line_break)
-                
-                # This is Clark Evans's interpretation (also in the spec
-                # examples):
-                #
-                #if folded and line_break == '\n':
-                #    if not breaks:
-                #        if self.peek() not in ' \t':
-                #            chunks.append(' ')
-                #        else:
-                #            chunks.append(line_break)
-                #else:
-                #    chunks.append(line_break)
-            else:
-                break
-
-        # Chomp the tail.
-        if chomping is not False:
-            chunks.append(line_break)
-        if chomping is True:
-            chunks.extend(breaks)
-
-        # We are done.
-        return ScalarToken(''.join(chunks), False, start_mark, end_mark,
-                style)
-
-    def scan_block_scalar_indicators(self, start_mark):
-        # See the specification for details.
-        chomping = None
-        increment = None
-        ch = self.peek()
-        if ch in '+-':
-            if ch == '+':
-                chomping = True
-            else:
-                chomping = False
-            self.forward()
-            ch = self.peek()
-            if ch in '0123456789':
-                increment = int(ch)
-                if increment == 0:
-                    raise ScannerError("while scanning a block scalar", start_mark,
-                            "expected indentation indicator in the range 1-9, but found 0",
-                            self.get_mark())
-                self.forward()
-        elif ch in '0123456789':
-            increment = int(ch)
-            if increment == 0:
-                raise ScannerError("while scanning a block scalar", start_mark,
-                        "expected indentation indicator in the range 1-9, but found 0",
-                        self.get_mark())
-            self.forward()
-            ch = self.peek()
-            if ch in '+-':
-                if ch == '+':
-                    chomping = True
-                else:
-                    chomping = False
-                self.forward()
-        ch = self.peek()
-        if ch not in '\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a block scalar", start_mark,
-                    "expected chomping or indentation indicators, but found %r"
-                    % ch, self.get_mark())
-        return chomping, increment
-
-    def scan_block_scalar_ignored_line(self, start_mark):
-        # See the specification for details.
-        while self.peek() == ' ':
-            self.forward()
-        if self.peek() == '#':
-            while self.peek() not in '\0\r\n\x85\u2028\u2029':
-                self.forward()
-        ch = self.peek()
-        if ch not in '\0\r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a block scalar", start_mark,
-                    "expected a comment or a line break, but found %r" % ch,
-                    self.get_mark())
-        self.scan_line_break()
-
-    def scan_block_scalar_indentation(self):
-        # See the specification for details.
-        chunks = []
-        max_indent = 0
-        end_mark = self.get_mark()
-        while self.peek() in ' \r\n\x85\u2028\u2029':
-            if self.peek() != ' ':
-                chunks.append(self.scan_line_break())
-                end_mark = self.get_mark()
-            else:
-                self.forward()
-                if self.column > max_indent:
-                    max_indent = self.column
-        return chunks, max_indent, end_mark
-
-    def scan_block_scalar_breaks(self, indent):
-        # See the specification for details.
-        chunks = []
-        end_mark = self.get_mark()
-        while self.column < indent and self.peek() == ' ':
-            self.forward()
-        while self.peek() in '\r\n\x85\u2028\u2029':
-            chunks.append(self.scan_line_break())
-            end_mark = self.get_mark()
-            while self.column < indent and self.peek() == ' ':
-                self.forward()
-        return chunks, end_mark
-
-    def scan_flow_scalar(self, style):
-        # See the specification for details.
-        # Note that we loose indentation rules for quoted scalars. Quoted
-        # scalars don't need to adhere indentation because " and ' clearly
-        # mark the beginning and the end of them. Therefore we are less
-        # restrictive then the specification requires. We only need to check
-        # that document separators are not included in scalars.
-        if style == '"':
-            double = True
-        else:
-            double = False
-        chunks = []
-        start_mark = self.get_mark()
-        quote = self.peek()
-        self.forward()
-        chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark))
-        while self.peek() != quote:
-            chunks.extend(self.scan_flow_scalar_spaces(double, start_mark))
-            chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark))
-        self.forward()
-        end_mark = self.get_mark()
-        return ScalarToken(''.join(chunks), False, start_mark, end_mark,
-                style)
-
-    ESCAPE_REPLACEMENTS = {
-        '0':    '\0',
-        'a':    '\x07',
-        'b':    '\x08',
-        't':    '\x09',
-        '\t':   '\x09',
-        'n':    '\x0A',
-        'v':    '\x0B',
-        'f':    '\x0C',
-        'r':    '\x0D',
-        'e':    '\x1B',
-        ' ':    '\x20',
-        '\"':   '\"',
-        '\\':   '\\',
-        '/':    '/',
-        'N':    '\x85',
-        '_':    '\xA0',
-        'L':    '\u2028',
-        'P':    '\u2029',
-    }
-
-    ESCAPE_CODES = {
-        'x':    2,
-        'u':    4,
-        'U':    8,
-    }
-
-    def scan_flow_scalar_non_spaces(self, double, start_mark):
-        # See the specification for details.
-        chunks = []
-        while True:
-            length = 0
-            while self.peek(length) not in '\'\"\\\0 \t\r\n\x85\u2028\u2029':
-                length += 1
-            if length:
-                chunks.append(self.prefix(length))
-                self.forward(length)
-            ch = self.peek()
-            if not double and ch == '\'' and self.peek(1) == '\'':
-                chunks.append('\'')
-                self.forward(2)
-            elif (double and ch == '\'') or (not double and ch in '\"\\'):
-                chunks.append(ch)
-                self.forward()
-            elif double and ch == '\\':
-                self.forward()
-                ch = self.peek()
-                if ch in self.ESCAPE_REPLACEMENTS:
-                    chunks.append(self.ESCAPE_REPLACEMENTS[ch])
-                    self.forward()
-                elif ch in self.ESCAPE_CODES:
-                    length = self.ESCAPE_CODES[ch]
-                    self.forward()
-                    for k in range(length):
-                        if self.peek(k) not in '0123456789ABCDEFabcdef':
-                            raise ScannerError("while scanning a double-quoted scalar", start_mark,
-                                    "expected escape sequence of %d hexdecimal numbers, but found %r" %
-                                        (length, self.peek(k)), self.get_mark())
-                    code = int(self.prefix(length), 16)
-                    chunks.append(chr(code))
-                    self.forward(length)
-                elif ch in '\r\n\x85\u2028\u2029':
-                    self.scan_line_break()
-                    chunks.extend(self.scan_flow_scalar_breaks(double, start_mark))
-                else:
-                    raise ScannerError("while scanning a double-quoted scalar", start_mark,
-                            "found unknown escape character %r" % ch, self.get_mark())
-            else:
-                return chunks
-
-    def scan_flow_scalar_spaces(self, double, start_mark):
-        # See the specification for details.
-        chunks = []
-        length = 0
-        while self.peek(length) in ' \t':
-            length += 1
-        whitespaces = self.prefix(length)
-        self.forward(length)
-        ch = self.peek()
-        if ch == '\0':
-            raise ScannerError("while scanning a quoted scalar", start_mark,
-                    "found unexpected end of stream", self.get_mark())
-        elif ch in '\r\n\x85\u2028\u2029':
-            line_break = self.scan_line_break()
-            breaks = self.scan_flow_scalar_breaks(double, start_mark)
-            if line_break != '\n':
-                chunks.append(line_break)
-            elif not breaks:
-                chunks.append(' ')
-            chunks.extend(breaks)
-        else:
-            chunks.append(whitespaces)
-        return chunks
-
-    def scan_flow_scalar_breaks(self, double, start_mark):
-        # See the specification for details.
-        chunks = []
-        while True:
-            # Instead of checking indentation, we check for document
-            # separators.
-            prefix = self.prefix(3)
-            if (prefix == '---' or prefix == '...')   \
-                    and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
-                raise ScannerError("while scanning a quoted scalar", start_mark,
-                        "found unexpected document separator", self.get_mark())
-            while self.peek() in ' \t':
-                self.forward()
-            if self.peek() in '\r\n\x85\u2028\u2029':
-                chunks.append(self.scan_line_break())
-            else:
-                return chunks
-
-    def scan_plain(self):
-        # See the specification for details.
-        # We add an additional restriction for the flow context:
-        #   plain scalars in the flow context cannot contain ',' or '?'.
-        # We also keep track of the `allow_simple_key` flag here.
-        # Indentation rules are loosed for the flow context.
-        chunks = []
-        start_mark = self.get_mark()
-        end_mark = start_mark
-        indent = self.indent+1
-        # We allow zero indentation for scalars, but then we need to check for
-        # document separators at the beginning of the line.
-        #if indent == 0:
-        #    indent = 1
-        spaces = []
-        while True:
-            length = 0
-            if self.peek() == '#':
-                break
-            while True:
-                ch = self.peek(length)
-                if ch in '\0 \t\r\n\x85\u2028\u2029'    \
-                        or (ch == ':' and
-                                self.peek(length+1) in '\0 \t\r\n\x85\u2028\u2029'
-                                      + (u',[]{}' if self.flow_level else u''))\
-                        or (self.flow_level and ch in ',?[]{}'):
-                    break
-                length += 1
-            if length == 0:
-                break
-            self.allow_simple_key = False
-            chunks.extend(spaces)
-            chunks.append(self.prefix(length))
-            self.forward(length)
-            end_mark = self.get_mark()
-            spaces = self.scan_plain_spaces(indent, start_mark)
-            if not spaces or self.peek() == '#' \
-                    or (not self.flow_level and self.column < indent):
-                break
-        return ScalarToken(''.join(chunks), True, start_mark, end_mark)
-
-    def scan_plain_spaces(self, indent, start_mark):
-        # See the specification for details.
-        # The specification is really confusing about tabs in plain scalars.
-        # We just forbid them completely. Do not use tabs in YAML!
-        chunks = []
-        length = 0
-        while self.peek(length) in ' ':
-            length += 1
-        whitespaces = self.prefix(length)
-        self.forward(length)
-        ch = self.peek()
-        if ch in '\r\n\x85\u2028\u2029':
-            line_break = self.scan_line_break()
-            self.allow_simple_key = True
-            prefix = self.prefix(3)
-            if (prefix == '---' or prefix == '...')   \
-                    and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
-                return
-            breaks = []
-            while self.peek() in ' \r\n\x85\u2028\u2029':
-                if self.peek() == ' ':
-                    self.forward()
-                else:
-                    breaks.append(self.scan_line_break())
-                    prefix = self.prefix(3)
-                    if (prefix == '---' or prefix == '...')   \
-                            and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
-                        return
-            if line_break != '\n':
-                chunks.append(line_break)
-            elif not breaks:
-                chunks.append(' ')
-            chunks.extend(breaks)
-        elif whitespaces:
-            chunks.append(whitespaces)
-        return chunks
-
-    def scan_tag_handle(self, name, start_mark):
-        # See the specification for details.
-        # For some strange reasons, the specification does not allow '_' in
-        # tag handles. I have allowed it anyway.
-        ch = self.peek()
-        if ch != '!':
-            raise ScannerError("while scanning a %s" % name, start_mark,
-                    "expected '!', but found %r" % ch, self.get_mark())
-        length = 1
-        ch = self.peek(length)
-        if ch != ' ':
-            while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'  \
-                    or ch in '-_':
-                length += 1
-                ch = self.peek(length)
-            if ch != '!':
-                self.forward(length)
-                raise ScannerError("while scanning a %s" % name, start_mark,
-                        "expected '!', but found %r" % ch, self.get_mark())
-            length += 1
-        value = self.prefix(length)
-        self.forward(length)
-        return value
-
-    def scan_tag_uri(self, name, start_mark):
-        # See the specification for details.
-        # Note: we do not check if URI is well-formed.
-        chunks = []
-        length = 0
-        ch = self.peek(length)
-        while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'  \
-                or ch in '-;/?:@&=+$,_.!~*\'()[]%':
-            if ch == '%':
-                chunks.append(self.prefix(length))
-                self.forward(length)
-                length = 0
-                chunks.append(self.scan_uri_escapes(name, start_mark))
-            else:
-                length += 1
-            ch = self.peek(length)
-        if length:
-            chunks.append(self.prefix(length))
-            self.forward(length)
-            length = 0
-        if not chunks:
-            raise ScannerError("while parsing a %s" % name, start_mark,
-                    "expected URI, but found %r" % ch, self.get_mark())
-        return ''.join(chunks)
-
-    def scan_uri_escapes(self, name, start_mark):
-        # See the specification for details.
-        codes = []
-        mark = self.get_mark()
-        while self.peek() == '%':
-            self.forward()
-            for k in range(2):
-                if self.peek(k) not in '0123456789ABCDEFabcdef':
-                    raise ScannerError("while scanning a %s" % name, start_mark,
-                            "expected URI escape sequence of 2 hexdecimal numbers, but found %r"
-                            % self.peek(k), self.get_mark())
-            codes.append(int(self.prefix(2), 16))
-            self.forward(2)
-        try:
-            value = bytes(codes).decode('utf-8')
-        except UnicodeDecodeError as exc:
-            raise ScannerError("while scanning a %s" % name, start_mark, str(exc), mark)
-        return value
-
-    def scan_line_break(self):
-        # Transforms:
-        #   '\r\n'      :   '\n'
-        #   '\r'        :   '\n'
-        #   '\n'        :   '\n'
-        #   '\x85'      :   '\n'
-        #   '\u2028'    :   '\u2028'
-        #   '\u2029     :   '\u2029'
-        #   default     :   ''
-        ch = self.peek()
-        if ch in '\r\n\x85':
-            if self.prefix(2) == '\r\n':
-                self.forward(2)
-            else:
-                self.forward()
-            return '\n'
-        elif ch in '\u2028\u2029':
-            self.forward()
-            return ch
-        return ''