def _eval_op(lhs, op, rhs):
    try:
        spec = Specifier(''.join([op.serialize(), rhs]))
    except InvalidSpecifier:
        pass
    else:
        return spec.contains(lhs)
    oper = _operators.get(op.serialize())
    if (oper is None):
        raise UndefinedComparison('Undefined {0!r} on {1!r} and {2!r}.'.format(op, lhs, rhs))
    return oper(lhs, rhs)
def _eval_op(lhs, op, rhs):
    try:
        spec = Specifier(.join([op.serialize(), rhs]))
    except InvalidSpecifier:
        pass
    else:
        return spec.contains(lhs)
    oper = _operators.get(op.serialize())
    if (oper is None):
        raise UndefinedComparison('Undefined {0!r} on {1!r} and {2!r}.'.format(op, lhs, rhs))
    return oper(lhs, rhs)