def _gcs_uri_rewriter(raw_uri):
  """Rewrite GCS file paths as required by the rewrite_uris method.

  The GCS rewriter performs no operations on the raw_path and simply returns
  it as the normalized URI. The docker path has the gs:// prefix replaced
  with gs/ so that it can be mounted inside a docker image.

  Args:
    raw_uri: (str) the raw GCS URI, prefix, or pattern.

  Returns:
    normalized: a cleaned version of the uri provided by command line.
    docker_path: the uri rewritten in the format required for mounting inside
                 a docker worker.
  """
  docker_path = raw_uri.replace('gs://', 'gs/', 1)
  return raw_uri, docker_path