'If more than one constant is associated with a particular value,
L{Values.lookupByValue} returns whichever of them is defined first.'

def test_lookupDuplicateByValue(self):

    class TRANSPORT_MESSAGE(Values, ):
        '\n                                                Message    types    supported    by    an    SSH    transport.\n                                                '
        KEX_DH_GEX_REQUEST_OLD = ValueConstant(30)
        KEXDH_INIT = ValueConstant(30)
    self.assertIs(TRANSPORT_MESSAGE.lookupByValue(30), TRANSPORT_MESSAGE.KEX_DH_GEX_REQUEST_OLD)
