Simple Stack in Python (Last-in-First-out)

stack.py

class Stack:
    def __init__(self):
        self._items = []

    def push(self, data):
        self._items.insert(0, data)

    def pop(self):
        return self._items.pop(0)

    def peek(self):
        return self._items[0]

    def size(self):
        return len(self._items)

    def is_empty(self):
        return self._items == []

    def stack_list(self):
        return self._items

a = Stack()
print("Is empty: ", a.is_empty())
# Is empty:  True

a.push("D1")
a.push("D2")
a.push("D3")

print("Stack list: ", a.stack_list())
# Stack list:  ['D3', 'D2', 'D1']

print("Stack size: ", a.size())
# Stack size:  3

print("Pop item: ", a.pop())
# Pop item:  D3

print("Pop item: ", a.pop())
# Pop item:  D2

print("Stack list: ", a.stack_list())
# Stack list:  ['D1']