code: def setup(app):
      
      global _is_sphinx
      _is_sphinx = True
      app.add_config_value('no_underscore_emphasis', False, 'env')
      app.add_config_value('m2r_parse_relative_links', False, 'env')
      app.add_config_value('m2r_anonymous_references', False, 'env')
      app.add_config_value('m2r_disable_inline_math', False, 'env')
      app.add_source_parser('.md', M2RParser)
      app.add_directive('mdinclude', MdInclude)
      metadata = dict(
          version=__version__,
          parallel_read_safe=True,
          parallel_write_safe=True,
      )
      return metadata
docs: When used for sphinx extension.