'Even + Odd  -> Odd
Even + Even -> Even
Odd  + Odd  -> Even'

@staticmethod
def Add(expr, assumptions):

    if expr.is_number:
        return AskEvenHandler._number(expr, assumptions)
    _result = True
    for arg in expr.args:
        if ask(Q.even(arg), assumptions):
            pass
        elif ask(Q.odd(arg), assumptions):
            _result = (not _result)
        else:
            break
    else:
        return _result
