stack.py

""" Stack implementation using Python List """

class Stack(object):

 def __init__(self):
 self.items = []

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

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

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

 def pop(self):
 if self.isEmpty():
 return None
 return self.items.pop()