stack.py

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

    def __repr__(self):
        return repr(self.items)

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

    def pop(self):
        return self.items.pop()

    def add(self):
        right = self.pop()
        left = self.pop()
        self.push(left + right)

    def sub(self):
        right = self.pop()
        left = self.pop()
        self.push(left - right)

    def mul(self):
        right = self.pop()
        left = self.pop()
        self.push(left * right)

    def div(self):
        right = self.pop()
        left = self.pop()
        self.push(left / right)

    def rotate(self):
        left = self.items[1:]
        right = [self.items[0]]
        self.items = left + right

    def swap(self):
        self.items[-2:] = self.items[-2:][::-1]