python 栈 ~

class Stack:def __init__(self):self.items = []def isEmpty(self):return len(self.items)==0def push(self,item):self.items.append(item)def pop(self):return self.items.pop()def peek(self):if not self.isEmpty():return self.items[len(self.items)-1]def size(self):return len(self.items)if __name__ == '__main__':s=Stack()print(s.isEmpty())s.push(4)s.push('dog')print(s.peek())s.push(True)print(s.size())print(s.isEmpty())s.push(8.4)print(s.pop())print(s.pop())print(s.size())