code: def _prefix_exists_in_gcs(gcs_prefix, credentials=None):
    
    gcs_service = _get_storage_service(credentials)
  
    bucket_name, prefix = gcs_prefix[len('gs://'):].split('/', 1)
    # documentation in
    # https://cloud.google.com/storage/docs/json_api/v1/objects/list
    request = gcs_service.objects().list(
        bucket=bucket_name, prefix=prefix, maxResults=1)
    response = request.execute()
    return response.get('items', None)
docs: Check whether there is a GCS object whose name starts with the prefix.
  
    Since GCS doesn't actually have folders, this is how we check instead.
  
    Args:
      gcs_prefix: The path; should start with 'gs://'.
      credentials: Optional credential to be used to load the file from gcs.
  
    Returns:
      True if the prefix matches at least one object in GCS.
  
    Raises:
      errors.HttpError: if it can't talk to the server