Python实现栈的操作

class Stack(object):
    def __init__(self):
        self.items = []

    def isEmpty(self):
        return self.items == []

    def push(self, item):
        self.items.append(item)

    def pop(self):
        return self.items.pop()

    def peek(self):
        return self.items[len(self.items) - 1]

    def size(self):
        return len(self.items)

if __name__ == '__main__':
    s=Stack()
    print(s.isEmpty())
    s.push("1")
    s.push("2")
    s.push("3")
    s.push("4")
    s.push("5")
    print(s.isEmpty())
    print(s.size())