def _truthtable(inputs, pcdata):
    """Return a truth table."""
    if len(inputs) == 0 and pcdata[0] in {PC_ZERO, PC_ONE}:
        return {
            PC_ZERO : TTZERO,
            PC_ONE  : TTONE
        }[pcdata[0]]
    elif len(inputs) == 1 and pcdata[0] == PC_ZERO and pcdata[1] == PC_ONE:
        return inputs[0]
    else:
        return TruthTable(inputs, pcdata)
Return a truth table.