class ArrayStack:    def __init__(self, volume):        self.vol = volume        self.count = 0        self.data = [-1] * volume
    def in_stack(self, value):        """入栈"""        if self.count == self.vol:            return False        self.data[self.count] = value        self.count += 1        return True
    def de_stack(self):        """出栈"""        if self.count == 0:            return None        self.count -= 1        return self.data[self.count]

def test_stack():    array_stack = ArrayStack(5)    data = ["a", "b", "c", "d", "e"]    for i in data:        array_stack.in_stack(i)    result = array_stack.in_stack("a")    assert not result    data.reverse()    for i in data:        assert i == array_stack.de_stack()    assert not array_stack.de_stack()

class LinkStack:    class Node:        def __init__(self, data):            self.data = data            self.next = None
    def __init__(self):        self.top = None
    def en_stack(self, value):        """入栈"""        new_node = self.Node(value)        if self.top is None:            self.top = new_node        else:            new_node.next = self.top            self.top = new_node
    def de_stack(self):        """出栈"""        if self.top is None:            return -1        result = self.top.data        self.top = self.top.next        return result

def test_link_stack():    link_stack = LinkStack()    data = [1, 2, 3, 4, 5]    for i in data:        link_stack.en_stack(i)    data.reverse()    for j in data:        assert j == link_stack.de_stack()    assert link_stack.de_stack() == -1