def gcs_to_bigstore_path(gs_path):
  """Converts a gs:// path to a /bigstore/ path.

  Args:
    gs_path: Path to convert from gcs to bigstore.
  Raises:
    ValueError: If provided path is not a gs:// path.
  Returns:
    Provided path with gs:// replaced by /bigstore/.
  """

  if not gs_path.startswith('gs://'):
    raise ValueError('Path must start with `gs://`: {}.'.format(gs_path))
  return gs_path.replace('gs://', '/bigstore/')