mkdocs.yml

site_name: My Docs
markdown_extensions:
    tox:
        slugify: !!python/object:myslugify.slugify

myslugify.py

import re
import unicodedata

def slugify(value, separator):
    """ Slugify a string, to make it URL friendly. """
    normalized = unicodedata.normalize('NFKD', value)
    try:
        normalized.encode('ascii')
        v = re.sub('[^\w\s-]', '', normalized).strip().lower()
    except UnicodeEncodeError:
        v = normalized
    return re.sub('[%s\s]+' % separator, separator, v)

slugify type error

% pyenv global             
3.4.3
% python --version         
Python 3.4.3
% mkdocs --version         
mkdocs, version 0.14.0
% ls
docs		mkdocs.yml	myslugify.py	site
% PYTHONPATH=. mkdocs build
Traceback (most recent call last):
  File "/Users/fatrow/.pyenv/versions/3.4.3/bin/mkdocs", line 11, in <module>
    sys.exit(cli())
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/click/core.py", line 700, in __call__
    return self.main(*args, **kwargs)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/click/core.py", line 680, in main
    rv = self.invoke(ctx)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/click/core.py", line 1027, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/click/core.py", line 873, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/click/core.py", line 508, in invoke
    return callback(*args, **kwargs)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/mkdocs/cli.py", line 133, in build_command
    site_dir=site_dir
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/mkdocs/config/base.py", line 143, in load_config
    cfg.load_file(config_file)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/mkdocs/config/base.py", line 96, in load_file
    return self.load_dict(utils.yaml_load(config_file))
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/mkdocs/utils/__init__.py", line 58, in yaml_load
    return yaml.load(source, Loader)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/yaml/__init__.py", line 72, in load
    return loader.get_single_data()
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/yaml/constructor.py", line 37, in get_single_data
    return self.construct_document(node)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/yaml/constructor.py", line 46, in construct_document
    for dummy in generator:
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/yaml/constructor.py", line 398, in construct_yaml_map
    value = self.construct_mapping(node)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/yaml/constructor.py", line 204, in construct_mapping
    return super().construct_mapping(node, deep=deep)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/yaml/constructor.py", line 129, in construct_mapping
    value = self.construct_object(value_node, deep=deep)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/yaml/constructor.py", line 91, in construct_object
    data = next(generator)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/yaml/constructor.py", line 575, in construct_python_object
    instance = self.make_python_instance(suffix, node, newobj=True)
  File "/Users/fatrow/.pyenv/versions/3.4.3/lib/python3.4/site-packages/yaml/constructor.py", line 556, in make_python_instance
    return cls(*args, **kwds)
TypeError: slugify() missing 2 required positional arguments: 'value' and 'separator'