message: Helpful ImportError message
diff: @@ -147,7 +147,9 @@ class TPUClusterResolver(ClusterResolver):
  if service is None and should_resolve:
  if not _GOOGLE_API_CLIENT_INSTALLED:
  raise ImportError('googleapiclient must be installed before using the '
  - 'TPU cluster resolver')
  + 'TPU cluster resolver. Execute: `pip install '
  + '--upgrade google-api-python-client` to install with '
  + 'pip.')
  self._service = discovery.build(
  'tpu', 'v1alpha1',
  