import tensorflow as tf

      string, out_string will contain a random integer casted to a string.
      Otherwise string_tensor is returned unchanged.

  """

  empty_string = tf.constant('', dtype=tf.string, name='EmptyString')

  random_source_id = tf.as_string(
    tf.random_uniform(shape=[], maxval=2 ** 63 - 1, dtype=tf.int64))

