1  class stack:
2    def __init__(self):
3         self.items = list()
4     #---------------------------
5     def isEmpty(self):
6         return len(self.items) == 0
7     #---------------------------
8     def length(self):
9         return len(self.items)
10    #------------------------------
11    def push(self, element):
12        self.items.append(element)
13    #-----------------------------
14    def top(self, element, underflow):
15        if self.isEmpty():
16            underflow = True
17        else:
18            underflow = False
19            element = self.items[len(self.items) - 1]
20        return element, underflow 
21    #-----------------------------
22    def pop(self, element, underflow):
23        if self.isEmpty():
24            underflow = True
25        else:
26            underflow = False
27            element = self.items.pop()
28        return element, underflow
29    #-------------------------
30    def display(self):
31        for i in range(len(self.items)):
32            print(self.items[i])