python列表模拟栈

class Stack():
    def __init__(self,len):
        self.stack =[]
        self.len = len
    def __repr__(self):#方便查看对象属性
        return str(self.stack)# 需要返回字符串
    def push(self,element):#压栈
        self.stack.append(element)
    def pop(self):#出栈
        if self.stack:
            self.stack.pop()
        else:
            return LookupError("栈已经空了")
    def is_empty(self):#判断是否为空
        return bool(self.stack)
    def full(self):# 判断栈是否满了
        if len(self.stack) == self.len :
            print("栈满了")
        else:
            print("栈没满")
    def find(self,element): #查找元素位置
        return self.stack.index(element)
    def peek(self):#返回栈顶元素
        if  self.is_empty():
            return self.stack[-1]
        else:
            print("栈是空的")

s = Stack(4)
print(s.is_empty())
s.push(4)
s.push(6)
s.push('a')
s.full()
print(s.peek())
print(s.find('a'))
# s.pop()
print(s)