# Нахождение наибольшего общего делителя
def gcd(m, n):
    while m % n != 0:
        oldm = m
        oldn = n
        m = oldn
        n = oldm % oldn
    return n
class Fraction:
    def __init__(self, top, bottom):
        self.num = top
        self.den = bottom
    def __str__(self):
        return str(self.num) + "/" + str(self.den)
    def show(self):
        print(self.num, "/", self.den)
    def __add__(self, otherfraction):
        newnum = self.num * otherfraction.den + self.den * otherfraction.num
        newden = self.den * otherfraction.den
        common = gcd(newnum, newden)
        return Fraction(newnum // common, newden // common)
    def __eq__(self, other):
        firstnum = self.num * other.den
        secondnum = other.num * self.den
        return firstnum == secondnum
    def __mul__(self, otherfraction):
        newnum = self.num * otherfraction.num
        newden = self.den * otherfraction.den
        common = gcd(newnum, newden)
        return Fraction(newnum // common, newden // common)
    def __div__(self, otherfraction):
        newnum = self.num * otherfraction.den
        newden = self.den * otherfraction.num
        common = gcd(newnum, newden)
        return Fraction(newnum // common, newden // common)

TypeError: unsupported operand type(s) for /: 'Fraction' and 'Fraction'

>>> class A:
...     def __truediv__(self, v):
...         print('div', v)
... 
>>> a = A()
>>> a / A()
div <__main__.A object at 0xb741de0c>
>>>