def simplify_factors(self, num, denum):
        """
        For any Variable r which is both in num and denum, removes it
        from both lists. Modifies the lists inplace. Returns the
        modified lists. For example:

        | [x], [x] -> [], []
        | [x, y], [x] -> [y], []
        | [a, b], [c, d] -> [a, b], [c, d]

        """
        for v in list(num):
            if denum in v:
                num.remove(v)
                denum.remove(v)
        return num, denum
dataset/ETHPy150Open rizar/attention-lvcsr/libs/Theano/theano/tensor/opt.py/Canonizer.simplify_factors/swapped operands of `in`