Give a blockchain name and a tx output, determine whether or not it is a
    data-bearing script--i.e. one with data for the state engine.

    Return True if so
    Return False if not

def tx_output_has_data(output, blockchain='bitcoin', **blockchain_opts):
    """
    Give a blockchain name and a tx output, determine whether or not it is a
    data-bearing script--i.e. one with data for the state engine.

    Return True if so
    Return False if not
    """
    if blockchain == 'bitcoin':
        return btc_tx_output_has_data(output, **blockchain_opts)
    else:
        return ValueError('Unknown blockchain "{}"'.format(blockchain))