best python stack implementation
class Stack:
     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)
