code: def serve_static(filename=None, prefix='', basedir=None):
      
      if not basedir:
          basedir = os.path.join(os.path.dirname(__file__), 'third_party')
      return send_from_directory(os.path.join(basedir, prefix), filename)
docs: Handler for static files: server filename in basedir/prefix.
  
      If not specified then basedir defaults to the local third_party
      directory.