栈

class Stack():
    def __init__(self):
        self.__items=[]
    # 判空
    def is_empty(self):
        return self.__items==[]
    # 循环遍历
    def travel(self):
        if self.is_empty():
            return False
        for i in self.__items:
            print(i,end='')
        print('')
    # 查看栈顶元素
    def peek(self):
        if self.is_empty():
            return False
        return self.__items[-1]
    # 栈的长度
    def length(self):
        return len(self.__items)
    # 添加元素
    def add(self,item):
        self.__items.append(item)
    # 删除元素
    def pop(self):
        self.__items.pop()
if __name__ == '__main__':
    ss=Stack()
    for i in range(10):
        ss.add(i)
    print(ss.length())
    ss.travel()
    print(ss.peek())
    ss.pop()
    ss.travel()