stack implementation using list in python.

ListStack.py

class ListStack:
    def __init__(self):
        self.stack = []

    def is_empty(self):
        return not self.stack

    def get_peek(self):
        assert(not self.is_empty())
        return self.stack[-1]
    
    def push(self, key):
        self.stack.append(key)

    def pop(self):
        self.stack.pop()