@staticmethod
    def Add(expr, assumptions):
        if expr.is_number:
            if expr.as_real_imag()[1]:
                return False
        return test_closed_group(expr, assumptions, Q.rational)
Rational + Rational     -> Rational
dataset/ETHPy150Open sympy/sympy/sympy/assumptions/handlers/sets.py/AskRationalHandler.Add