code: def _parse_gcs_uri(self, raw_uri):
      
      # Assume URI is a directory path.
      raw_uri = directory_fmt(raw_uri)
      _, docker_path = _gcs_uri_rewriter(raw_uri)
      docker_uri = os.path.join(self._relative_path, docker_path)
      return docker_uri
docs: Return a valid docker_path for a GCS bucket.