code: def _file_exists_in_gcs(gcs_file_path, credentials=None):
    
    gcs_service = _get_storage_service(credentials)
  
    bucket_name, object_name = gcs_file_path[len('gs://'):].split('/', 1)
    request = gcs_service.objects().get(
        bucket=bucket_name, object=object_name, projection='noAcl')
    try:
      request.execute()
      return True
    except errors.HttpError:
      return False
docs: Check whether the file exists, in GCS.
  
    Args:
      gcs_file_path: The target file path; should have the 'gs://' prefix.
      credentials: Optional credential to be used to load the file from gcs.
  
    Returns:
      True if the file's there.