'Add two Rats, or a Rat and a number.'

def __add__(self, other):

    if isint(other):
        other = Rat(other)
    if isRat(other):
        return Rat(((self.__num * other.__den) + (other.__num * self.__den)), (self.__den * other.__den))
    if isnum(other):
        return (float(self) + other)
    return NotImplemented
