python链表的乘法问题

   def __mul__(self, other):
        if type(other) is Node:
            n1,n2 = self.values,other.values
            product = [p[0]*p[1] for p in zip(n1,n2)]
            return Node.build(product)
        if other<0 or type(other) is not int:
            raise TypeError("other is a non-negetive Integer")
        if other==0:return Node()
        ret = self.copy()
        for _ in range(1,other):
            self += ret
        return self
 
    __rmul__ = __mul__
 
 
'''
>>> a = Node() + range(1,3)
>>> a * 0
Node(None->None)
>>> a * 1
Node(1->2->None)
>>> a * 2
Node(1->2->1->2->None)
>>> a * 5
Node(1->2->1->2->1->2->1->2->1->2->None)
>>>
>>> 3 * a
Node(1->2->1->2->1->2->None)
>>> a
Node(1->2->None)
>>> a *= 5
>>> a
Node(1->2->1->2->1->2->1->2->1->2->None)
>>>
>>>
>>> a = Node() + range(1,8)
>>> b = Node(2) * 7
>>> a * b
Node(2->4->6->8->10->12->14->None)
>>> b * a
Node(2->4->6->8->10->12->14->None)
>>>
'''