我想编写一个允许算术运算符的fraction类，但是当我定义div方法时，它似乎不能除法。

from math import gcd

class Fraction:
    def __init__(self, n, d):
        self.n = n
        self.d = d
    def __add__(self, other):
        newn = self.n * other.d + self.d * other.n
        newd = self.d * other.d
        common = gcd(newn, newd)
        return Fraction(newn/common, newd/common)
    def __sub__(self, other):
        newn = self.n * other.d - self.d * other.n
        newd = self.d * other.d
        common = gcd(newn, newd)
        return Fraction(newn/common, newd/common)
    def __div__(self, other):
        newn = self.n * other.d
        newd = self.d * other.n
        common = gcd(newn, newd)
        return Fraction(newn/common, newd/common)
    def __mul__(self, other):
        newn = self.n * other.n
        newd = self.d * other.d
        common = gcd(newn, newd)
        return Fraction(newn/common, newd/common)
    def __repr__(self):
        return "{}/{}".format(int(self.n), int(self.d))

print(Fraction(1, 2) / Fraction(1, 4))