--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.7/site-packages/ruamel/yaml/parser.py	Sat May 02 07:14:21 2020 -0400
@@ -0,0 +1,794 @@
+# coding: utf-8
+
+from __future__ import absolute_import
+
+# The following YAML grammar is LL(1) and is parsed by a recursive descent
+# parser.
+#
+# stream            ::= STREAM-START implicit_document? explicit_document*
+#                                                                   STREAM-END
+# implicit_document ::= block_node DOCUMENT-END*
+# explicit_document ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+# block_node_or_indentless_sequence ::=
+#                       ALIAS
+#                       | properties (block_content |
+#                                                   indentless_block_sequence)?
+#                       | block_content
+#                       | indentless_block_sequence
+# block_node        ::= ALIAS
+#                       | properties block_content?
+#                       | block_content
+# flow_node         ::= ALIAS
+#                       | properties flow_content?
+#                       | flow_content
+# properties        ::= TAG ANCHOR? | ANCHOR TAG?
+# block_content     ::= block_collection | flow_collection | SCALAR
+# flow_content      ::= flow_collection | SCALAR
+# block_collection  ::= block_sequence | block_mapping
+# flow_collection   ::= flow_sequence | flow_mapping
+# block_sequence    ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)*
+#                                                                   BLOCK-END
+# indentless_sequence   ::= (BLOCK-ENTRY block_node?)+
+# block_mapping     ::= BLOCK-MAPPING_START
+#                       ((KEY block_node_or_indentless_sequence?)?
+#                       (VALUE block_node_or_indentless_sequence?)?)*
+#                       BLOCK-END
+# flow_sequence     ::= FLOW-SEQUENCE-START
+#                       (flow_sequence_entry FLOW-ENTRY)*
+#                       flow_sequence_entry?
+#                       FLOW-SEQUENCE-END
+# flow_sequence_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+# flow_mapping      ::= FLOW-MAPPING-START
+#                       (flow_mapping_entry FLOW-ENTRY)*
+#                       flow_mapping_entry?
+#                       FLOW-MAPPING-END
+# flow_mapping_entry    ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+#
+# FIRST sets:
+#
+# stream: { STREAM-START }
+# explicit_document: { DIRECTIVE DOCUMENT-START }
+# implicit_document: FIRST(block_node)
+# block_node: { ALIAS TAG ANCHOR SCALAR BLOCK-SEQUENCE-START
+#                  BLOCK-MAPPING-START FLOW-SEQUENCE-START FLOW-MAPPING-START }
+# flow_node: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START FLOW-MAPPING-START }
+# block_content: { BLOCK-SEQUENCE-START BLOCK-MAPPING-START
+#                               FLOW-SEQUENCE-START FLOW-MAPPING-START SCALAR }
+# flow_content: { FLOW-SEQUENCE-START FLOW-MAPPING-START SCALAR }
+# block_collection: { BLOCK-SEQUENCE-START BLOCK-MAPPING-START }
+# flow_collection: { FLOW-SEQUENCE-START FLOW-MAPPING-START }
+# block_sequence: { BLOCK-SEQUENCE-START }
+# block_mapping: { BLOCK-MAPPING-START }
+# block_node_or_indentless_sequence: { ALIAS ANCHOR TAG SCALAR
+#               BLOCK-SEQUENCE-START BLOCK-MAPPING-START FLOW-SEQUENCE-START
+#               FLOW-MAPPING-START BLOCK-ENTRY }
+# indentless_sequence: { ENTRY }
+# flow_collection: { FLOW-SEQUENCE-START FLOW-MAPPING-START }
+# flow_sequence: { FLOW-SEQUENCE-START }
+# flow_mapping: { FLOW-MAPPING-START }
+# flow_sequence_entry: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START
+#                                                    FLOW-MAPPING-START KEY }
+# flow_mapping_entry: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START
+#                                                    FLOW-MAPPING-START KEY }
+
+# need to have full path with import, as pkg_resources tries to load parser.py in __init__.py
+# only to not do anything with the package afterwards
+# and for Jython too
+
+
+from ruamel.yaml.error import MarkedYAMLError
+from ruamel.yaml.tokens import *  # NOQA
+from ruamel.yaml.events import *  # NOQA
+from ruamel.yaml.scanner import Scanner, RoundTripScanner, ScannerError  # NOQA
+from ruamel.yaml.compat import utf8, nprint, nprintf  # NOQA
+
+if False:  # MYPY
+    from typing import Any, Dict, Optional, List  # NOQA
+
+__all__ = ['Parser', 'RoundTripParser', 'ParserError']
+
+
+class ParserError(MarkedYAMLError):
+    pass
+
+
+class Parser(object):
+    # Since writing a recursive-descendant parser is a straightforward task, we
+    # do not give many comments here.
+
+    DEFAULT_TAGS = {u'!': u'!', u'!!': u'tag:yaml.org,2002:'}
+
+    def __init__(self, loader):
+        # type: (Any) -> None
+        self.loader = loader
+        if self.loader is not None and getattr(self.loader, '_parser', None) is None:
+            self.loader._parser = self
+        self.reset_parser()
+
+    def reset_parser(self):
+        # type: () -> None
+        # Reset the state attributes (to clear self-references)
+        self.current_event = None
+        self.yaml_version = None
+        self.tag_handles = {}  # type: Dict[Any, Any]
+        self.states = []  # type: List[Any]
+        self.marks = []  # type: List[Any]
+        self.state = self.parse_stream_start  # type: Any
+
+    def dispose(self):
+        # type: () -> None
+        self.reset_parser()
+
+    @property
+    def scanner(self):
+        # type: () -> Any
+        if hasattr(self.loader, 'typ'):
+            return self.loader.scanner
+        return self.loader._scanner
+
+    @property
+    def resolver(self):
+        # type: () -> Any
+        if hasattr(self.loader, 'typ'):
+            return self.loader.resolver
+        return self.loader._resolver
+
+    def check_event(self, *choices):
+        # type: (Any) -> bool
+        # Check the type of the next event.
+        if self.current_event is None:
+            if self.state:
+                self.current_event = self.state()
+        if self.current_event is not None:
+            if not choices:
+                return True
+            for choice in choices:
+                if isinstance(self.current_event, choice):
+                    return True
+        return False
+
+    def peek_event(self):
+        # type: () -> Any
+        # Get the next event.
+        if self.current_event is None:
+            if self.state:
+                self.current_event = self.state()
+        return self.current_event
+
+    def get_event(self):
+        # type: () -> Any
+        # Get the next event and proceed further.
+        if self.current_event is None:
+            if self.state:
+                self.current_event = self.state()
+        value = self.current_event
+        self.current_event = None
+        return value
+
+    # stream    ::= STREAM-START implicit_document? explicit_document*
+    #                                                               STREAM-END
+    # implicit_document ::= block_node DOCUMENT-END*
+    # explicit_document ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
+
+    def parse_stream_start(self):
+        # type: () -> Any
+        # Parse the stream start.
+        token = self.scanner.get_token()
+        token.move_comment(self.scanner.peek_token())
+        event = StreamStartEvent(token.start_mark, token.end_mark, encoding=token.encoding)
+
+        # Prepare the next state.
+        self.state = self.parse_implicit_document_start
+
+        return event
+
+    def parse_implicit_document_start(self):
+        # type: () -> Any
+        # Parse an implicit document.
+        if not self.scanner.check_token(DirectiveToken, DocumentStartToken, StreamEndToken):
+            self.tag_handles = self.DEFAULT_TAGS
+            token = self.scanner.peek_token()
+            start_mark = end_mark = token.start_mark
+            event = DocumentStartEvent(start_mark, end_mark, explicit=False)
+
+            # Prepare the next state.
+            self.states.append(self.parse_document_end)
+            self.state = self.parse_block_node
+
+            return event
+
+        else:
+            return self.parse_document_start()
+
+    def parse_document_start(self):
+        # type: () -> Any
+        # Parse any extra document end indicators.
+        while self.scanner.check_token(DocumentEndToken):
+            self.scanner.get_token()
+        # Parse an explicit document.
+        if not self.scanner.check_token(StreamEndToken):
+            token = self.scanner.peek_token()
+            start_mark = token.start_mark
+            version, tags = self.process_directives()
+            if not self.scanner.check_token(DocumentStartToken):
+                raise ParserError(
+                    None,
+                    None,
+                    "expected '<document start>', but found %r" % self.scanner.peek_token().id,
+                    self.scanner.peek_token().start_mark,
+                )
+            token = self.scanner.get_token()
+            end_mark = token.end_mark
+            event = DocumentStartEvent(
+                start_mark, end_mark, explicit=True, version=version, tags=tags
+            )  # type: Any
+            self.states.append(self.parse_document_end)
+            self.state = self.parse_document_content
+        else:
+            # Parse the end of the stream.
+            token = self.scanner.get_token()
+            event = StreamEndEvent(token.start_mark, token.end_mark, comment=token.comment)
+            assert not self.states
+            assert not self.marks
+            self.state = None
+        return event
+
+    def parse_document_end(self):
+        # type: () -> Any
+        # Parse the document end.
+        token = self.scanner.peek_token()
+        start_mark = end_mark = token.start_mark
+        explicit = False
+        if self.scanner.check_token(DocumentEndToken):
+            token = self.scanner.get_token()
+            end_mark = token.end_mark
+            explicit = True
+        event = DocumentEndEvent(start_mark, end_mark, explicit=explicit)
+
+        # Prepare the next state.
+        if self.resolver.processing_version == (1, 1):
+            self.state = self.parse_document_start
+        else:
+            self.state = self.parse_implicit_document_start
+
+        return event
+
+    def parse_document_content(self):
+        # type: () -> Any
+        if self.scanner.check_token(
+            DirectiveToken, DocumentStartToken, DocumentEndToken, StreamEndToken
+        ):
+            event = self.process_empty_scalar(self.scanner.peek_token().start_mark)
+            self.state = self.states.pop()
+            return event
+        else:
+            return self.parse_block_node()
+
+    def process_directives(self):
+        # type: () -> Any
+        self.yaml_version = None
+        self.tag_handles = {}
+        while self.scanner.check_token(DirectiveToken):
+            token = self.scanner.get_token()
+            if token.name == u'YAML':
+                if self.yaml_version is not None:
+                    raise ParserError(
+                        None, None, 'found duplicate YAML directive', token.start_mark
+                    )
+                major, minor = token.value
+                if major != 1:
+                    raise ParserError(
+                        None,
+                        None,
+                        'found incompatible YAML document (version 1.* is ' 'required)',
+                        token.start_mark,
+                    )
+                self.yaml_version = token.value
+            elif token.name == u'TAG':
+                handle, prefix = token.value
+                if handle in self.tag_handles:
+                    raise ParserError(
+                        None, None, 'duplicate tag handle %r' % utf8(handle), token.start_mark
+                    )
+                self.tag_handles[handle] = prefix
+        if bool(self.tag_handles):
+            value = self.yaml_version, self.tag_handles.copy()  # type: Any
+        else:
+            value = self.yaml_version, None
+        for key in self.DEFAULT_TAGS:
+            if key not in self.tag_handles:
+                self.tag_handles[key] = self.DEFAULT_TAGS[key]
+        return value
+
+    # block_node_or_indentless_sequence ::= ALIAS
+    #               | properties (block_content | indentless_block_sequence)?
+    #               | block_content
+    #               | indentless_block_sequence
+    # block_node    ::= ALIAS
+    #                   | properties block_content?
+    #                   | block_content
+    # flow_node     ::= ALIAS
+    #                   | properties flow_content?
+    #                   | flow_content
+    # properties    ::= TAG ANCHOR? | ANCHOR TAG?
+    # block_content     ::= block_collection | flow_collection | SCALAR
+    # flow_content      ::= flow_collection | SCALAR
+    # block_collection  ::= block_sequence | block_mapping
+    # flow_collection   ::= flow_sequence | flow_mapping
+
+    def parse_block_node(self):
+        # type: () -> Any
+        return self.parse_node(block=True)
+
+    def parse_flow_node(self):
+        # type: () -> Any
+        return self.parse_node()
+
+    def parse_block_node_or_indentless_sequence(self):
+        # type: () -> Any
+        return self.parse_node(block=True, indentless_sequence=True)
+
+    def transform_tag(self, handle, suffix):
+        # type: (Any, Any) -> Any
+        return self.tag_handles[handle] + suffix
+
+    def parse_node(self, block=False, indentless_sequence=False):
+        # type: (bool, bool) -> Any
+        if self.scanner.check_token(AliasToken):
+            token = self.scanner.get_token()
+            event = AliasEvent(token.value, token.start_mark, token.end_mark)  # type: Any
+            self.state = self.states.pop()
+            return event
+
+        anchor = None
+        tag = None
+        start_mark = end_mark = tag_mark = None
+        if self.scanner.check_token(AnchorToken):
+            token = self.scanner.get_token()
+            start_mark = token.start_mark
+            end_mark = token.end_mark
+            anchor = token.value
+            if self.scanner.check_token(TagToken):
+                token = self.scanner.get_token()
+                tag_mark = token.start_mark
+                end_mark = token.end_mark
+                tag = token.value
+        elif self.scanner.check_token(TagToken):
+            token = self.scanner.get_token()
+            start_mark = tag_mark = token.start_mark
+            end_mark = token.end_mark
+            tag = token.value
+            if self.scanner.check_token(AnchorToken):
+                token = self.scanner.get_token()
+                start_mark = tag_mark = token.start_mark
+                end_mark = token.end_mark
+                anchor = token.value
+        if tag is not None:
+            handle, suffix = tag
+            if handle is not None:
+                if handle not in self.tag_handles:
+                    raise ParserError(
+                        'while parsing a node',
+                        start_mark,
+                        'found undefined tag handle %r' % utf8(handle),
+                        tag_mark,
+                    )
+                tag = self.transform_tag(handle, suffix)
+            else:
+                tag = suffix
+        # if tag == u'!':
+        #     raise ParserError("while parsing a node", start_mark,
+        #             "found non-specific tag '!'", tag_mark,
+        #      "Please check 'http://pyyaml.org/wiki/YAMLNonSpecificTag'
+        #     and share your opinion.")
+        if start_mark is None:
+            start_mark = end_mark = self.scanner.peek_token().start_mark
+        event = None
+        implicit = tag is None or tag == u'!'
+        if indentless_sequence and self.scanner.check_token(BlockEntryToken):
+            comment = None
+            pt = self.scanner.peek_token()
+            if pt.comment and pt.comment[0]:
+                comment = [pt.comment[0], []]
+                pt.comment[0] = None
+            end_mark = self.scanner.peek_token().end_mark
+            event = SequenceStartEvent(
+                anchor, tag, implicit, start_mark, end_mark, flow_style=False, comment=comment
+            )
+            self.state = self.parse_indentless_sequence_entry
+            return event
+
+        if self.scanner.check_token(ScalarToken):
+            token = self.scanner.get_token()
+            # self.scanner.peek_token_same_line_comment(token)
+            end_mark = token.end_mark
+            if (token.plain and tag is None) or tag == u'!':
+                implicit = (True, False)
+            elif tag is None:
+                implicit = (False, True)
+            else:
+                implicit = (False, False)
+            # nprint('se', token.value, token.comment)
+            event = ScalarEvent(
+                anchor,
+                tag,
+                implicit,
+                token.value,
+                start_mark,
+                end_mark,
+                style=token.style,
+                comment=token.comment,
+            )
+            self.state = self.states.pop()
+        elif self.scanner.check_token(FlowSequenceStartToken):
+            pt = self.scanner.peek_token()
+            end_mark = pt.end_mark
+            event = SequenceStartEvent(
+                anchor,
+                tag,
+                implicit,
+                start_mark,
+                end_mark,
+                flow_style=True,
+                comment=pt.comment,
+            )
+            self.state = self.parse_flow_sequence_first_entry
+        elif self.scanner.check_token(FlowMappingStartToken):
+            pt = self.scanner.peek_token()
+            end_mark = pt.end_mark
+            event = MappingStartEvent(
+                anchor,
+                tag,
+                implicit,
+                start_mark,
+                end_mark,
+                flow_style=True,
+                comment=pt.comment,
+            )
+            self.state = self.parse_flow_mapping_first_key
+        elif block and self.scanner.check_token(BlockSequenceStartToken):
+            end_mark = self.scanner.peek_token().start_mark
+            # should inserting the comment be dependent on the
+            # indentation?
+            pt = self.scanner.peek_token()
+            comment = pt.comment
+            # nprint('pt0', type(pt))
+            if comment is None or comment[1] is None:
+                comment = pt.split_comment()
+            # nprint('pt1', comment)
+            event = SequenceStartEvent(
+                anchor, tag, implicit, start_mark, end_mark, flow_style=False, comment=comment
+            )
+            self.state = self.parse_block_sequence_first_entry
+        elif block and self.scanner.check_token(BlockMappingStartToken):
+            end_mark = self.scanner.peek_token().start_mark
+            comment = self.scanner.peek_token().comment
+            event = MappingStartEvent(
+                anchor, tag, implicit, start_mark, end_mark, flow_style=False, comment=comment
+            )
+            self.state = self.parse_block_mapping_first_key
+        elif anchor is not None or tag is not None:
+            # Empty scalars are allowed even if a tag or an anchor is
+            # specified.
+            event = ScalarEvent(anchor, tag, (implicit, False), "", start_mark, end_mark)
+            self.state = self.states.pop()
+        else:
+            if block:
+                node = 'block'
+            else:
+                node = 'flow'
+            token = self.scanner.peek_token()
+            raise ParserError(
+                'while parsing a %s node' % node,
+                start_mark,
+                'expected the node content, but found %r' % token.id,
+                token.start_mark,
+            )
+        return event
+
+    # block_sequence ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)*
+    #                                                               BLOCK-END
+
+    def parse_block_sequence_first_entry(self):
+        # type: () -> Any
+        token = self.scanner.get_token()
+        # move any comment from start token
+        # token.move_comment(self.scanner.peek_token())
+        self.marks.append(token.start_mark)
+        return self.parse_block_sequence_entry()
+
+    def parse_block_sequence_entry(self):
+        # type: () -> Any
+        if self.scanner.check_token(BlockEntryToken):
+            token = self.scanner.get_token()
+            token.move_comment(self.scanner.peek_token())
+            if not self.scanner.check_token(BlockEntryToken, BlockEndToken):
+                self.states.append(self.parse_block_sequence_entry)
+                return self.parse_block_node()
+            else:
+                self.state = self.parse_block_sequence_entry
+                return self.process_empty_scalar(token.end_mark)
+        if not self.scanner.check_token(BlockEndToken):
+            token = self.scanner.peek_token()
+            raise ParserError(
+                'while parsing a block collection',
+                self.marks[-1],
+                'expected <block end>, but found %r' % token.id,
+                token.start_mark,
+            )
+        token = self.scanner.get_token()  # BlockEndToken
+        event = SequenceEndEvent(token.start_mark, token.end_mark, comment=token.comment)
+        self.state = self.states.pop()
+        self.marks.pop()
+        return event
+
+    # indentless_sequence ::= (BLOCK-ENTRY block_node?)+
+
+    # indentless_sequence?
+    # sequence:
+    # - entry
+    #  - nested
+
+    def parse_indentless_sequence_entry(self):
+        # type: () -> Any
+        if self.scanner.check_token(BlockEntryToken):
+            token = self.scanner.get_token()
+            token.move_comment(self.scanner.peek_token())
+            if not self.scanner.check_token(
+                BlockEntryToken, KeyToken, ValueToken, BlockEndToken
+            ):
+                self.states.append(self.parse_indentless_sequence_entry)
+                return self.parse_block_node()
+            else:
+                self.state = self.parse_indentless_sequence_entry
+                return self.process_empty_scalar(token.end_mark)
+        token = self.scanner.peek_token()
+        event = SequenceEndEvent(token.start_mark, token.start_mark, comment=token.comment)
+        self.state = self.states.pop()
+        return event
+
+    # block_mapping     ::= BLOCK-MAPPING_START
+    #                       ((KEY block_node_or_indentless_sequence?)?
+    #                       (VALUE block_node_or_indentless_sequence?)?)*
+    #                       BLOCK-END
+
+    def parse_block_mapping_first_key(self):
+        # type: () -> Any
+        token = self.scanner.get_token()
+        self.marks.append(token.start_mark)
+        return self.parse_block_mapping_key()
+
+    def parse_block_mapping_key(self):
+        # type: () -> Any
+        if self.scanner.check_token(KeyToken):
+            token = self.scanner.get_token()
+            token.move_comment(self.scanner.peek_token())
+            if not self.scanner.check_token(KeyToken, ValueToken, BlockEndToken):
+                self.states.append(self.parse_block_mapping_value)
+                return self.parse_block_node_or_indentless_sequence()
+            else:
+                self.state = self.parse_block_mapping_value
+                return self.process_empty_scalar(token.end_mark)
+        if self.resolver.processing_version > (1, 1) and self.scanner.check_token(ValueToken):
+            self.state = self.parse_block_mapping_value
+            return self.process_empty_scalar(self.scanner.peek_token().start_mark)
+        if not self.scanner.check_token(BlockEndToken):
+            token = self.scanner.peek_token()
+            raise ParserError(
+                'while parsing a block mapping',
+                self.marks[-1],
+                'expected <block end>, but found %r' % token.id,
+                token.start_mark,
+            )
+        token = self.scanner.get_token()
+        token.move_comment(self.scanner.peek_token())
+        event = MappingEndEvent(token.start_mark, token.end_mark, comment=token.comment)
+        self.state = self.states.pop()
+        self.marks.pop()
+        return event
+
+    def parse_block_mapping_value(self):
+        # type: () -> Any
+        if self.scanner.check_token(ValueToken):
+            token = self.scanner.get_token()
+            # value token might have post comment move it to e.g. block
+            if self.scanner.check_token(ValueToken):
+                token.move_comment(self.scanner.peek_token())
+            else:
+                if not self.scanner.check_token(KeyToken):
+                    token.move_comment(self.scanner.peek_token(), empty=True)
+                # else: empty value for this key cannot move token.comment
+            if not self.scanner.check_token(KeyToken, ValueToken, BlockEndToken):
+                self.states.append(self.parse_block_mapping_key)
+                return self.parse_block_node_or_indentless_sequence()
+            else:
+                self.state = self.parse_block_mapping_key
+                comment = token.comment
+                if comment is None:
+                    token = self.scanner.peek_token()
+                    comment = token.comment
+                    if comment:
+                        token._comment = [None, comment[1]]
+                        comment = [comment[0], None]
+                return self.process_empty_scalar(token.end_mark, comment=comment)
+        else:
+            self.state = self.parse_block_mapping_key
+            token = self.scanner.peek_token()
+            return self.process_empty_scalar(token.start_mark)
+
+    # flow_sequence     ::= FLOW-SEQUENCE-START
+    #                       (flow_sequence_entry FLOW-ENTRY)*
+    #                       flow_sequence_entry?
+    #                       FLOW-SEQUENCE-END
+    # flow_sequence_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+    #
+    # Note that while production rules for both flow_sequence_entry and
+    # flow_mapping_entry are equal, their interpretations are different.
+    # For `flow_sequence_entry`, the part `KEY flow_node? (VALUE flow_node?)?`
+    # generate an inline mapping (set syntax).
+
+    def parse_flow_sequence_first_entry(self):
+        # type: () -> Any
+        token = self.scanner.get_token()
+        self.marks.append(token.start_mark)
+        return self.parse_flow_sequence_entry(first=True)
+
+    def parse_flow_sequence_entry(self, first=False):
+        # type: (bool) -> Any
+        if not self.scanner.check_token(FlowSequenceEndToken):
+            if not first:
+                if self.scanner.check_token(FlowEntryToken):
+                    self.scanner.get_token()
+                else:
+                    token = self.scanner.peek_token()
+                    raise ParserError(
+                        'while parsing a flow sequence',
+                        self.marks[-1],
+                        "expected ',' or ']', but got %r" % token.id,
+                        token.start_mark,
+                    )
+
+            if self.scanner.check_token(KeyToken):
+                token = self.scanner.peek_token()
+                event = MappingStartEvent(
+                    None, None, True, token.start_mark, token.end_mark, flow_style=True
+                )  # type: Any
+                self.state = self.parse_flow_sequence_entry_mapping_key
+                return event
+            elif not self.scanner.check_token(FlowSequenceEndToken):
+                self.states.append(self.parse_flow_sequence_entry)
+                return self.parse_flow_node()
+        token = self.scanner.get_token()
+        event = SequenceEndEvent(token.start_mark, token.end_mark, comment=token.comment)
+        self.state = self.states.pop()
+        self.marks.pop()
+        return event
+
+    def parse_flow_sequence_entry_mapping_key(self):
+        # type: () -> Any
+        token = self.scanner.get_token()
+        if not self.scanner.check_token(ValueToken, FlowEntryToken, FlowSequenceEndToken):
+            self.states.append(self.parse_flow_sequence_entry_mapping_value)
+            return self.parse_flow_node()
+        else:
+            self.state = self.parse_flow_sequence_entry_mapping_value
+            return self.process_empty_scalar(token.end_mark)
+
+    def parse_flow_sequence_entry_mapping_value(self):
+        # type: () -> Any
+        if self.scanner.check_token(ValueToken):
+            token = self.scanner.get_token()
+            if not self.scanner.check_token(FlowEntryToken, FlowSequenceEndToken):
+                self.states.append(self.parse_flow_sequence_entry_mapping_end)
+                return self.parse_flow_node()
+            else:
+                self.state = self.parse_flow_sequence_entry_mapping_end
+                return self.process_empty_scalar(token.end_mark)
+        else:
+            self.state = self.parse_flow_sequence_entry_mapping_end
+            token = self.scanner.peek_token()
+            return self.process_empty_scalar(token.start_mark)
+
+    def parse_flow_sequence_entry_mapping_end(self):
+        # type: () -> Any
+        self.state = self.parse_flow_sequence_entry
+        token = self.scanner.peek_token()
+        return MappingEndEvent(token.start_mark, token.start_mark)
+
+    # flow_mapping  ::= FLOW-MAPPING-START
+    #                   (flow_mapping_entry FLOW-ENTRY)*
+    #                   flow_mapping_entry?
+    #                   FLOW-MAPPING-END
+    # flow_mapping_entry    ::= flow_node | KEY flow_node? (VALUE flow_node?)?
+
+    def parse_flow_mapping_first_key(self):
+        # type: () -> Any
+        token = self.scanner.get_token()
+        self.marks.append(token.start_mark)
+        return self.parse_flow_mapping_key(first=True)
+
+    def parse_flow_mapping_key(self, first=False):
+        # type: (Any) -> Any
+        if not self.scanner.check_token(FlowMappingEndToken):
+            if not first:
+                if self.scanner.check_token(FlowEntryToken):
+                    self.scanner.get_token()
+                else:
+                    token = self.scanner.peek_token()
+                    raise ParserError(
+                        'while parsing a flow mapping',
+                        self.marks[-1],
+                        "expected ',' or '}', but got %r" % token.id,
+                        token.start_mark,
+                    )
+            if self.scanner.check_token(KeyToken):
+                token = self.scanner.get_token()
+                if not self.scanner.check_token(
+                    ValueToken, FlowEntryToken, FlowMappingEndToken
+                ):
+                    self.states.append(self.parse_flow_mapping_value)
+                    return self.parse_flow_node()
+                else:
+                    self.state = self.parse_flow_mapping_value
+                    return self.process_empty_scalar(token.end_mark)
+            elif self.resolver.processing_version > (1, 1) and self.scanner.check_token(
+                ValueToken
+            ):
+                self.state = self.parse_flow_mapping_value
+                return self.process_empty_scalar(self.scanner.peek_token().end_mark)
+            elif not self.scanner.check_token(FlowMappingEndToken):
+                self.states.append(self.parse_flow_mapping_empty_value)
+                return self.parse_flow_node()
+        token = self.scanner.get_token()
+        event = MappingEndEvent(token.start_mark, token.end_mark, comment=token.comment)
+        self.state = self.states.pop()
+        self.marks.pop()
+        return event
+
+    def parse_flow_mapping_value(self):
+        # type: () -> Any
+        if self.scanner.check_token(ValueToken):
+            token = self.scanner.get_token()
+            if not self.scanner.check_token(FlowEntryToken, FlowMappingEndToken):
+                self.states.append(self.parse_flow_mapping_key)
+                return self.parse_flow_node()
+            else:
+                self.state = self.parse_flow_mapping_key
+                return self.process_empty_scalar(token.end_mark)
+        else:
+            self.state = self.parse_flow_mapping_key
+            token = self.scanner.peek_token()
+            return self.process_empty_scalar(token.start_mark)
+
+    def parse_flow_mapping_empty_value(self):
+        # type: () -> Any
+        self.state = self.parse_flow_mapping_key
+        return self.process_empty_scalar(self.scanner.peek_token().start_mark)
+
+    def process_empty_scalar(self, mark, comment=None):
+        # type: (Any, Any) -> Any
+        return ScalarEvent(None, None, (True, False), "", mark, mark, comment=comment)
+
+
+class RoundTripParser(Parser):
+    """roundtrip is a safe loader, that wants to see the unmangled tag"""
+
+    def transform_tag(self, handle, suffix):
+        # type: (Any, Any) -> Any
+        # return self.tag_handles[handle]+suffix
+        if handle == '!!' and suffix in (
+            u'null',
+            u'bool',
+            u'int',
+            u'float',
+            u'binary',
+            u'timestamp',
+            u'omap',
+            u'pairs',
+            u'set',
+            u'str',
+            u'seq',
+            u'map',
+        ):
+            return Parser.transform_tag(self, handle, suffix)
+        return handle + suffix