--- a/env/lib/python3.7/site-packages/networkx/readwrite/gml.py	Thu May 14 16:47:39 2020 -0400
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,842 +0,0 @@
-# encoding: utf-8
-#    Copyright (C) 2008-2019 by
-#    Aric Hagberg <hagberg@lanl.gov>
-#    Dan Schult <dschult@colgate.edu>
-#    Pieter Swart <swart@lanl.gov>
-#    All rights reserved.
-#    BSD license.
-#
-# Author: Aric Hagberg (hagberg@lanl.gov)
-"""
-Read graphs in GML format.
-
-"GML, the Graph Modelling Language, is our proposal for a portable
-file format for graphs. GML's key features are portability, simple
-syntax, extensibility and flexibility. A GML file consists of a
-hierarchical key-value lists. Graphs can be annotated with arbitrary
-data structures. The idea for a common file format was born at the
-GD'95; this proposal is the outcome of many discussions. GML is the
-standard file format in the Graphlet graph editor system. It has been
-overtaken and adapted by several other systems for drawing graphs."
-
-GML files are stored using a 7-bit ASCII encoding with any extended
-ASCII characters (iso8859-1) appearing as HTML character entities.
-You will need to give some thought into how the exported data should
-interact with different languages and even different Python versions.
-Re-importing from gml is also a concern.
-
-Without specifying a `stringizer`/`destringizer`, the code is capable of
-handling `int`/`float`/`str`/`dict`/`list` data as required by the GML
-specification.  For other data types, you need to explicitly supply a
-`stringizer`/`destringizer`.
-
-For better interoperability of data generated by Python 2 and Python 3,
-we've provided `literal_stringizer` and `literal_destringizer`.
-
-For additional documentation on the GML file format, please see the
-`GML website <http://www.infosun.fim.uni-passau.de/Graphlet/GML/gml-tr.html>`_.
-
-Several example graphs in GML format may be found on Mark Newman's
-`Network data page <http://www-personal.umich.edu/~mejn/netdata/>`_.
-"""
-try:
-    try:
-        from cStringIO import StringIO
-    except ImportError:
-        from StringIO import StringIO
-except ImportError:
-    from io import StringIO
-from ast import literal_eval
-from collections import defaultdict
-import networkx as nx
-from networkx.exception import NetworkXError
-from networkx.utils import open_file
-
-import re
-try:
-    import htmlentitydefs
-except ImportError:
-    # Python 3.x
-    import html.entities as htmlentitydefs
-
-__all__ = ['read_gml', 'parse_gml', 'generate_gml', 'write_gml']
-
-
-try:
-    long
-except NameError:
-    long = int
-try:
-    unicode
-except NameError:
-    unicode = str
-try:
-    unichr
-except NameError:
-    unichr = chr
-try:
-    literal_eval(r"u'\u4444'")
-except SyntaxError:
-    # Remove 'u' prefixes in unicode literals in Python 3
-    def rtp_fix_unicode(s): return s[1:]
-else:
-    rtp_fix_unicode = None
-
-
-def escape(text):
-    """Use XML character references to escape characters.
-
-    Use XML character references for unprintable or non-ASCII
-    characters, double quotes and ampersands in a string
-    """
-    def fixup(m):
-        ch = m.group(0)
-        return '&#' + str(ord(ch)) + ';'
-
-    text = re.sub('[^ -~]|[&"]', fixup, text)
-    return text if isinstance(text, str) else str(text)
-
-
-def unescape(text):
-    """Replace XML character references with the referenced characters"""
-    def fixup(m):
-        text = m.group(0)
-        if text[1] == '#':
-            # Character reference
-            if text[2] == 'x':
-                code = int(text[3:-1], 16)
-            else:
-                code = int(text[2:-1])
-        else:
-            # Named entity
-            try:
-                code = htmlentitydefs.name2codepoint[text[1:-1]]
-            except KeyError:
-                return text  # leave unchanged
-        try:
-            return chr(code) if code < 256 else unichr(code)
-        except (ValueError, OverflowError):
-            return text  # leave unchanged
-
-    return re.sub("&(?:[0-9A-Za-z]+|#(?:[0-9]+|x[0-9A-Fa-f]+));", fixup, text)
-
-
-def literal_destringizer(rep):
-    """Convert a Python literal to the value it represents.
-
-    Parameters
-    ----------
-    rep : string
-        A Python literal.
-
-    Returns
-    -------
-    value : object
-        The value of the Python literal.
-
-    Raises
-    ------
-    ValueError
-        If `rep` is not a Python literal.
-    """
-    if isinstance(rep, (str, unicode)):
-        orig_rep = rep
-        if rtp_fix_unicode is not None:
-            rep = rtp_fix_unicode(rep)
-        try:
-            return literal_eval(rep)
-        except SyntaxError:
-            raise ValueError('%r is not a valid Python literal' % (orig_rep,))
-    else:
-        raise ValueError('%r is not a string' % (rep,))
-
-
-@open_file(0, mode='rb')
-def read_gml(path, label='label', destringizer=None):
-    """Read graph in GML format from `path`.
-
-    Parameters
-    ----------
-    path : filename or filehandle
-        The filename or filehandle to read from.
-
-    label : string, optional
-        If not None, the parsed nodes will be renamed according to node
-        attributes indicated by `label`. Default value: 'label'.
-
-    destringizer : callable, optional
-        A `destringizer` that recovers values stored as strings in GML. If it
-        cannot convert a string to a value, a `ValueError` is raised. Default
-        value : None.
-
-    Returns
-    -------
-    G : NetworkX graph
-        The parsed graph.
-
-    Raises
-    ------
-    NetworkXError
-        If the input cannot be parsed.
-
-    See Also
-    --------
-    write_gml, parse_gml, literal_destringizer
-
-    Notes
-    -----
-    GML files are stored using a 7-bit ASCII encoding with any extended
-    ASCII characters (iso8859-1) appearing as HTML character entities.
-    Without specifying a `stringizer`/`destringizer`, the code is capable of
-    handling `int`/`float`/`str`/`dict`/`list` data as required by the GML
-    specification.  For other data types, you need to explicitly supply a
-    `stringizer`/`destringizer`.
-
-    For additional documentation on the GML file format, please see the
-    `GML url <http://www.infosun.fim.uni-passau.de/Graphlet/GML/gml-tr.html>`_.
-
-    See the module docstring :mod:`networkx.readwrite.gml` for more details.
-
-    Examples
-    --------
-    >>> G = nx.path_graph(4)
-    >>> nx.write_gml(G, 'test.gml')
-    >>> H = nx.read_gml('test.gml')
-    """
-    def filter_lines(lines):
-        for line in lines:
-            try:
-                line = line.decode('ascii')
-            except UnicodeDecodeError:
-                raise NetworkXError('input is not ASCII-encoded')
-            if not isinstance(line, str):
-                lines = str(lines)
-            if line and line[-1] == '\n':
-                line = line[:-1]
-            yield line
-
-    G = parse_gml_lines(filter_lines(path), label, destringizer)
-    return G
-
-
-def parse_gml(lines, label='label', destringizer=None):
-    """Parse GML graph from a string or iterable.
-
-    Parameters
-    ----------
-    lines : string or iterable of strings
-       Data in GML format.
-
-    label : string, optional
-        If not None, the parsed nodes will be renamed according to node
-        attributes indicated by `label`. Default value: 'label'.
-
-    destringizer : callable, optional
-        A `destringizer` that recovers values stored as strings in GML. If it
-        cannot convert a string to a value, a `ValueError` is raised. Default
-        value : None.
-
-    Returns
-    -------
-    G : NetworkX graph
-        The parsed graph.
-
-    Raises
-    ------
-    NetworkXError
-        If the input cannot be parsed.
-
-    See Also
-    --------
-    write_gml, read_gml, literal_destringizer
-
-    Notes
-    -----
-    This stores nested GML attributes as dictionaries in the NetworkX graph,
-    node, and edge attribute structures.
-
-    GML files are stored using a 7-bit ASCII encoding with any extended
-    ASCII characters (iso8859-1) appearing as HTML character entities.
-    Without specifying a `stringizer`/`destringizer`, the code is capable of
-    handling `int`/`float`/`str`/`dict`/`list` data as required by the GML
-    specification.  For other data types, you need to explicitly supply a
-    `stringizer`/`destringizer`.
-
-    For additional documentation on the GML file format, please see the
-    `GML url <http://www.infosun.fim.uni-passau.de/Graphlet/GML/gml-tr.html>`_.
-
-    See the module docstring :mod:`networkx.readwrite.gml` for more details.
-    """
-    def decode_line(line):
-        if isinstance(line, bytes):
-            try:
-                line.decode('ascii')
-            except UnicodeDecodeError:
-                raise NetworkXError('input is not ASCII-encoded')
-        if not isinstance(line, str):
-            line = str(line)
-        return line
-
-    def filter_lines(lines):
-        if isinstance(lines, (str, unicode)):
-            lines = decode_line(lines)
-            lines = lines.splitlines()
-            for line in lines:
-                yield line
-        else:
-            for line in lines:
-                line = decode_line(line)
-                if line and line[-1] == '\n':
-                    line = line[:-1]
-                if line.find('\n') != -1:
-                    raise NetworkXError('input line contains newline')
-                yield line
-
-    G = parse_gml_lines(filter_lines(lines), label, destringizer)
-    return G
-
-
-def parse_gml_lines(lines, label, destringizer):
-    """Parse GML `lines` into a graph.
-    """
-    def tokenize():
-        patterns = [
-            r'[A-Za-z][0-9A-Za-z_]*\b',  # keys
-            # reals
-            r'[+-]?(?:[0-9]*\.[0-9]+|[0-9]+\.[0-9]*)(?:[Ee][+-]?[0-9]+)?',
-            r'[+-]?[0-9]+',   # ints
-            r'".*?"',         # strings
-            r'\[',            # dict start
-            r'\]',            # dict end
-            r'#.*$|\s+'       # comments and whitespaces
-        ]
-        tokens = re.compile(
-            '|'.join('(' + pattern + ')' for pattern in patterns))
-        lineno = 0
-        for line in lines:
-            length = len(line)
-            pos = 0
-            while pos < length:
-                match = tokens.match(line, pos)
-                if match is not None:
-                    for i in range(len(patterns)):
-                        group = match.group(i + 1)
-                        if group is not None:
-                            if i == 0:    # keys
-                                value = group.rstrip()
-                            elif i == 1:  # reals
-                                value = float(group)
-                            elif i == 2:  # ints
-                                value = int(group)
-                            else:
-                                value = group
-                            if i != 6:    # comments and whitespaces
-                                yield (i, value, lineno + 1, pos + 1)
-                            pos += len(group)
-                            break
-                else:
-                    raise NetworkXError('cannot tokenize %r at (%d, %d)' %
-                                        (line[pos:], lineno + 1, pos + 1))
-            lineno += 1
-        yield (None, None, lineno + 1, 1)  # EOF
-
-    def unexpected(curr_token, expected):
-        category, value, lineno, pos = curr_token
-        raise NetworkXError(
-            'expected %s, found %s at (%d, %d)' %
-            (expected, repr(value) if value is not None else 'EOF', lineno,
-             pos))
-
-    def consume(curr_token, category, expected):
-        if curr_token[0] == category:
-            return next(tokens)
-        unexpected(curr_token, expected)
-
-    def parse_kv(curr_token):
-        dct = defaultdict(list)
-        while curr_token[0] == 0:  # keys
-            key = curr_token[1]
-            curr_token = next(tokens)
-            category = curr_token[0]
-            if category == 1 or category == 2:  # reals or ints
-                value = curr_token[1]
-                curr_token = next(tokens)
-            elif category == 3:  # strings
-                value = unescape(curr_token[1][1:-1])
-                if destringizer:
-                    try:
-                        value = destringizer(value)
-                    except ValueError:
-                        pass
-                curr_token = next(tokens)
-            elif category == 4:  # dict start
-                curr_token, value = parse_dict(curr_token)
-            else:
-                # Allow for string convertible id and label values
-                if key in ("id", "label", "source", "target"):
-                    try:
-                        # String convert the token value
-                        value = unescape(str(curr_token[1]))
-                        if destringizer:
-                            try:
-                                value = destringizer(value)
-                            except ValueError:
-                                pass
-                        curr_token = next(tokens)
-                    except Exception:
-                        msg = "an int, float, string, '[' or string" + \
-                              " convertable ASCII value for node id or label"
-                        unexpected(curr_token, msg)
-                else:  # Otherwise error out
-                    unexpected(curr_token, "an int, float, string or '['")
-            dct[key].append(value)
-        dct = {key: (value if not isinstance(value, list) or len(value) != 1
-                     else value[0]) for key, value in dct.items()}
-        return curr_token, dct
-
-    def parse_dict(curr_token):
-        curr_token = consume(curr_token, 4, "'['")    # dict start
-        curr_token, dct = parse_kv(curr_token)
-        curr_token = consume(curr_token, 5, "']'")  # dict end
-        return curr_token, dct
-
-    def parse_graph():
-        curr_token, dct = parse_kv(next(tokens))
-        if curr_token[0] is not None:  # EOF
-            unexpected(curr_token, 'EOF')
-        if 'graph' not in dct:
-            raise NetworkXError('input contains no graph')
-        graph = dct['graph']
-        if isinstance(graph, list):
-            raise NetworkXError('input contains more than one graph')
-        return graph
-
-    tokens = tokenize()
-    graph = parse_graph()
-
-    directed = graph.pop('directed', False)
-    multigraph = graph.pop('multigraph', False)
-    if not multigraph:
-        G = nx.DiGraph() if directed else nx.Graph()
-    else:
-        G = nx.MultiDiGraph() if directed else nx.MultiGraph()
-    G.graph.update((key, value) for key, value in graph.items()
-                   if key != 'node' and key != 'edge')
-
-    def pop_attr(dct, category, attr, i):
-        try:
-            return dct.pop(attr)
-        except KeyError:
-            raise NetworkXError(
-                "%s #%d has no '%s' attribute" % (category, i, attr))
-
-    nodes = graph.get('node', [])
-    mapping = {}
-    node_labels = set()
-    for i, node in enumerate(nodes if isinstance(nodes, list) else [nodes]):
-        id = pop_attr(node, 'node', 'id', i)
-        if id in G:
-            raise NetworkXError('node id %r is duplicated' % (id,))
-        if label is not None and label != 'id':
-            node_label = pop_attr(node, 'node', label, i)
-            if node_label in node_labels:
-                raise NetworkXError('node label %r is duplicated' %
-                                    (node_label,))
-            node_labels.add(node_label)
-            mapping[id] = node_label
-        G.add_node(id, **node)
-
-    edges = graph.get('edge', [])
-    for i, edge in enumerate(edges if isinstance(edges, list) else [edges]):
-        source = pop_attr(edge, 'edge', 'source', i)
-        target = pop_attr(edge, 'edge', 'target', i)
-        if source not in G:
-            raise NetworkXError(
-                'edge #%d has an undefined source %r' % (i, source))
-        if target not in G:
-            raise NetworkXError(
-                'edge #%d has an undefined target %r' % (i, target))
-        if not multigraph:
-            if not G.has_edge(source, target):
-                G.add_edge(source, target, **edge)
-            else:
-                msg = "edge #%d (%r%s%r) is duplicated.\n"
-                msg2 = 'Hint: If multigraph add "multigraph 1" to file header.'
-                info = (i, source, '->' if directed else '--', target)
-                raise nx.NetworkXError((msg % info) + msg2)
-        else:
-            key = edge.pop('key', None)
-            if key is not None and G.has_edge(source, target, key):
-                raise nx.NetworkXError(
-                    'edge #%d (%r%s%r, %r) is duplicated' %
-                    (i, source, '->' if directed else '--', target, key))
-            G.add_edge(source, target, key, **edge)
-
-    if label is not None and label != 'id':
-        G = nx.relabel_nodes(G, mapping)
-    return G
-
-
-def literal_stringizer(value):
-    """Convert a `value` to a Python literal in GML representation.
-
-    Parameters
-    ----------
-    value : object
-        The `value` to be converted to GML representation.
-
-    Returns
-    -------
-    rep : string
-        A double-quoted Python literal representing value. Unprintable
-        characters are replaced by XML character references.
-
-    Raises
-    ------
-    ValueError
-        If `value` cannot be converted to GML.
-
-    Notes
-    -----
-    `literal_stringizer` is largely the same as `repr` in terms of
-    functionality but attempts prefix `unicode` and `bytes` literals with
-    `u` and `b` to provide better interoperability of data generated by
-    Python 2 and Python 3.
-
-    The original value can be recovered using the
-    :func:`networkx.readwrite.gml.literal_destringizer` function.
-    """
-    def stringize(value):
-        if isinstance(value, (int, long, bool)) or value is None:
-            if value is True:  # GML uses 1/0 for boolean values.
-                buf.write(str(1))
-            elif value is False:
-                buf.write(str(0))
-            else:
-                buf.write(str(value))
-        elif isinstance(value, unicode):
-            text = repr(value)
-            if text[0] != 'u':
-                try:
-                    value.encode('latin1')
-                except UnicodeEncodeError:
-                    text = 'u' + text
-            buf.write(text)
-        elif isinstance(value, (float, complex, str, bytes)):
-            buf.write(repr(value))
-        elif isinstance(value, list):
-            buf.write('[')
-            first = True
-            for item in value:
-                if not first:
-                    buf.write(',')
-                else:
-                    first = False
-                stringize(item)
-            buf.write(']')
-        elif isinstance(value, tuple):
-            if len(value) > 1:
-                buf.write('(')
-                first = True
-                for item in value:
-                    if not first:
-                        buf.write(',')
-                    else:
-                        first = False
-                    stringize(item)
-                buf.write(')')
-            elif value:
-                buf.write('(')
-                stringize(value[0])
-                buf.write(',)')
-            else:
-                buf.write('()')
-        elif isinstance(value, dict):
-            buf.write('{')
-            first = True
-            for key, value in value.items():
-                if not first:
-                    buf.write(',')
-                else:
-                    first = False
-                stringize(key)
-                buf.write(':')
-                stringize(value)
-            buf.write('}')
-        elif isinstance(value, set):
-            buf.write('{')
-            first = True
-            for item in value:
-                if not first:
-                    buf.write(',')
-                else:
-                    first = False
-                stringize(item)
-            buf.write('}')
-        else:
-            raise ValueError(
-                '%r cannot be converted into a Python literal' % (value,))
-
-    buf = StringIO()
-    stringize(value)
-    return buf.getvalue()
-
-
-def generate_gml(G, stringizer=None):
-    r"""Generate a single entry of the graph `G` in GML format.
-
-    Parameters
-    ----------
-    G : NetworkX graph
-        The graph to be converted to GML.
-
-    stringizer : callable, optional
-        A `stringizer` which converts non-int/non-float/non-dict values into
-        strings. If it cannot convert a value into a string, it should raise a
-        `ValueError` to indicate that. Default value: None.
-
-    Returns
-    -------
-    lines: generator of strings
-        Lines of GML data. Newlines are not appended.
-
-    Raises
-    ------
-    NetworkXError
-        If `stringizer` cannot convert a value into a string, or the value to
-        convert is not a string while `stringizer` is None.
-
-    See Also
-    --------
-    literal_stringizer
-
-    Notes
-    -----
-    Graph attributes named 'directed', 'multigraph', 'node' or
-    'edge', node attributes named 'id' or 'label', edge attributes
-    named 'source' or 'target' (or 'key' if `G` is a multigraph)
-    are ignored because these attribute names are used to encode the graph
-    structure.
-
-    GML files are stored using a 7-bit ASCII encoding with any extended
-    ASCII characters (iso8859-1) appearing as HTML character entities.
-    Without specifying a `stringizer`/`destringizer`, the code is capable of
-    handling `int`/`float`/`str`/`dict`/`list` data as required by the GML
-    specification.  For other data types, you need to explicitly supply a
-    `stringizer`/`destringizer`.
-
-    For additional documentation on the GML file format, please see the
-    `GML url <http://www.infosun.fim.uni-passau.de/Graphlet/GML/gml-tr.html>`_.
-
-    See the module docstring :mod:`networkx.readwrite.gml` for more details.
-
-    Examples
-    --------
-    >>> G = nx.Graph()
-    >>> G.add_node("1")
-    >>> print("\n".join(nx.generate_gml(G)))
-    graph [
-      node [
-        id 0
-        label "1"
-      ]
-    ]
-    >>> G = nx.OrderedMultiGraph([("a", "b"), ("a", "b")])
-    >>> print("\n".join(nx.generate_gml(G)))
-    graph [
-      multigraph 1
-      node [
-        id 0
-        label "a"
-      ]
-      node [
-        id 1
-        label "b"
-      ]
-      edge [
-        source 0
-        target 1
-        key 0
-      ]
-      edge [
-        source 0
-        target 1
-        key 1
-      ]
-    ]
-    """
-    valid_keys = re.compile('^[A-Za-z][0-9A-Za-z]*$')
-
-    def stringize(key, value, ignored_keys, indent, in_list=False):
-        if not isinstance(key, (str, unicode)):
-            raise NetworkXError('%r is not a string' % (key,))
-        if not valid_keys.match(key):
-            raise NetworkXError('%r is not a valid key' % (key,))
-        if not isinstance(key, str):
-            key = str(key)
-        if key not in ignored_keys:
-            if isinstance(value, (int, long, bool)):
-                if key == 'label':
-                    yield indent + key + ' "' + str(value) + '"'
-                elif value is True:
-                    # python bool is an instance of int
-                    yield indent + key + ' 1'
-                elif value is False:
-                    yield indent + key + ' 0'
-                # GML only supports signed 32-bit integers
-                elif value < -2**31 or value >= 2**31:
-                    yield indent + key + ' "' + str(value) + '"'
-                else:
-                    yield indent + key + ' ' + str(value)
-            elif isinstance(value, float):
-                text = repr(value).upper()
-                # GML requires that a real literal contain a decimal point, but
-                # repr may not output a decimal point when the mantissa is
-                # integral and hence needs fixing.
-                epos = text.rfind('E')
-                if epos != -1 and text.find('.', 0, epos) == -1:
-                    text = text[:epos] + '.' + text[epos:]
-                if key == 'label':
-                    yield indent + key + ' "' + text + '"'
-                else:
-                    yield indent + key + ' ' + text
-            elif isinstance(value, dict):
-                yield indent + key + ' ['
-                next_indent = indent + '  '
-                for key, value in value.items():
-                    for line in stringize(key, value, (), next_indent):
-                        yield line
-                yield indent + ']'
-            elif isinstance(value, (list, tuple)) and key != 'label' \
-                    and value and not in_list:
-                next_indent = indent + '  '
-                for val in value:
-                    for line in stringize(key, val, (), next_indent, True):
-                        yield line
-            else:
-                if stringizer:
-                    try:
-                        value = stringizer(value)
-                    except ValueError:
-                        raise NetworkXError(
-                            '%r cannot be converted into a string' % (value,))
-                if not isinstance(value, (str, unicode)):
-                    raise NetworkXError('%r is not a string' % (value,))
-                yield indent + key + ' "' + escape(value) + '"'
-
-    multigraph = G.is_multigraph()
-    yield 'graph ['
-
-    # Output graph attributes
-    if G.is_directed():
-        yield '  directed 1'
-    if multigraph:
-        yield '  multigraph 1'
-    ignored_keys = {'directed', 'multigraph', 'node', 'edge'}
-    for attr, value in G.graph.items():
-        for line in stringize(attr, value, ignored_keys, '  '):
-            yield line
-
-    # Output node data
-    node_id = dict(zip(G, range(len(G))))
-    ignored_keys = {'id', 'label'}
-    for node, attrs in G.nodes.items():
-        yield '  node ['
-        yield '    id ' + str(node_id[node])
-        for line in stringize('label', node, (), '    '):
-            yield line
-        for attr, value in attrs.items():
-            for line in stringize(attr, value, ignored_keys, '    '):
-                yield line
-        yield '  ]'
-
-    # Output edge data
-    ignored_keys = {'source', 'target'}
-    kwargs = {'data': True}
-    if multigraph:
-        ignored_keys.add('key')
-        kwargs['keys'] = True
-    for e in G.edges(**kwargs):
-        yield '  edge ['
-        yield '    source ' + str(node_id[e[0]])
-        yield '    target ' + str(node_id[e[1]])
-        if multigraph:
-            for line in stringize('key', e[2], (), '    '):
-                yield line
-        for attr, value in e[-1].items():
-            for line in stringize(attr, value, ignored_keys, '    '):
-                yield line
-        yield '  ]'
-    yield ']'
-
-
-@open_file(1, mode='wb')
-def write_gml(G, path, stringizer=None):
-    """Write a graph `G` in GML format to the file or file handle `path`.
-
-    Parameters
-    ----------
-    G : NetworkX graph
-        The graph to be converted to GML.
-
-    path : filename or filehandle
-        The filename or filehandle to write. Files whose names end with .gz or
-        .bz2 will be compressed.
-
-    stringizer : callable, optional
-        A `stringizer` which converts non-int/non-float/non-dict values into
-        strings. If it cannot convert a value into a string, it should raise a
-        `ValueError` to indicate that. Default value: None.
-
-    Raises
-    ------
-    NetworkXError
-        If `stringizer` cannot convert a value into a string, or the value to
-        convert is not a string while `stringizer` is None.
-
-    See Also
-    --------
-    read_gml, generate_gml, literal_stringizer
-
-    Notes
-    -----
-    Graph attributes named 'directed', 'multigraph', 'node' or
-    'edge', node attributes named 'id' or 'label', edge attributes
-    named 'source' or 'target' (or 'key' if `G` is a multigraph)
-    are ignored because these attribute names are used to encode the graph
-    structure.
-
-    GML files are stored using a 7-bit ASCII encoding with any extended
-    ASCII characters (iso8859-1) appearing as HTML character entities.
-    Without specifying a `stringizer`/`destringizer`, the code is capable of
-    handling `int`/`float`/`str`/`dict`/`list` data as required by the GML
-    specification.  For other data types, you need to explicitly supply a
-    `stringizer`/`destringizer`.
-
-    Note that while we allow non-standard GML to be read from a file, we make
-    sure to write GML format. In particular, underscores are not allowed in
-    attribute names.
-    For additional documentation on the GML file format, please see the
-    `GML url <http://www.infosun.fim.uni-passau.de/Graphlet/GML/gml-tr.html>`_.
-
-    See the module docstring :mod:`networkx.readwrite.gml` for more details.
-
-    Examples
-    --------
-    >>> G = nx.path_graph(4)
-    >>> nx.write_gml(G, "test.gml")
-
-    Filenames ending in .gz or .bz2 will be compressed.
-
-    >>> nx.write_gml(G, "test.gml.gz")
-    """
-    for line in generate_gml(G, stringizer):
-        path.write((line + '\n').encode('ascii'))
-
-
-# fixture for pytest
-def teardown_module(module):
-    import os
-    for fname in ['test.gml', 'test.gml.gz']:
-        if os.path.isfile(fname):
-            os.unlink(fname)