code: def add_favicon_path(self, path: str) -> None:
          
          spec = web.URLSpec(
              '/(favicon.ico)',
              StaticFileHandler,
              dict(path=path)
          )
          # Need some check
          handlers = self.handlers[0][1]
          handlers.append(spec)
docs: Add path to serve favicon file.
  
          ``path`` should be a directory, which contains favicon file
          (``favicon.ico``) for your app.