def CreateFile(filename):
  """Create a GCS file with GCS client lib.

  Args:
    filename: GCS filename.

  Returns:
    The corresponding string blobkey for this GCS file.
  """
  with gcs.open(filename, 'w') as f:
    f.write('abcde\n')

  blobstore_filename = '/gs' + filename
  return blobstore.create_gs_key(blobstore_filename)
Create a GCS file with GCS client lib.

  Args:
    filename: GCS filename.

  Returns:
    The corresponding string blobkey for this GCS file.