docs: def overlay_url_for(endpoint, filename=None, **values):
      """
      Replace flasks url_for() function to allow usage without template changes
  
      If the requested endpoint is static or ending in .static, it tries to serve a bower asset, otherwise it will pass
      the arguments to flask.url_for()
  
      See http://flask.pocoo.org/docs/0.10/api/#flask.url_for
      """
      default_url_for_args = values.copy()
      if filename:
          default_url_for_args['filename'] = filename
  
      if endpoint == 'static' or endpoint.endswith('.static'):
  
          if os.path.sep in filename:
              filename_parts = filename.split(os.path.sep)
              component = filename_parts[0]
              # Using * magic here to expand list
              filename = os.path.join(*filename_parts[1:])
  
              returned_url = build_url(component, filename, **values)
  
              if returned_url is not None:
                  return returned_url
  
      return None