def data_gen_sig2() -> repr_dataset.RepresentativeDataset:
      """Generates tuple-style samples for signature 'sig2'.

      The first element of the tuple identifies the signature key the input data
      is for.

      Yields:
        Representative sample for 'sig2'.
      """
      for _ in range(4):
        yield {'conv_input': random_ops.random_uniform(shape=(1, 3, 4, 3))}