stack.py

class Stack:
    """A stack is an abstract data type that serves as a collection of
    elements with two principal operations: push() and pop(). push() adds an
    element to the top of the stack, and pop() removes an element from the top
    of a stack. The order in which elements come off of a stack are
    Last In, First Out (LIFO).

    https://en.wikipedia.org/wiki/Stack_(abstract_data_type)
    """

    def __init__(self, limit: int = 10):
        self.stack = []
        self.limit = limit

    def __bool__(self) -> bool:
        return bool(self.stack)

    def __str__(self) -> str:
        return str(self.stack)

    def push(self, data):
        """ Push an element to the top of the stack."""
        if len(self.stack) >= self.limit:
            raise StackOverflowError
        self.stack.append(data)

    def pop(self):
        """ Pop an element off of the top of the stack."""
        if self.is_empty():
            raise IndexError("pop from an empty stack")
        return self.stack.pop()

    def peek(self):
        """ Peek at the top-most element of the stack."""
        if self.is_empty():
            raise IndexError("peek from an empty stack")
        return self.stack[-1]

    def is_empty(self) -> bool:
        """ Check if a stack is empty."""
        return not bool(self.stack)

    def is_full(self) -> bool:
        return self.size() == self.limit

    def size(self) -> int:
        """ Return the size of the stack."""
        return len(self.stack)

    def __contains__(self, item) -> bool:
        """Check if item is in stack"""
        return item in self.stack


class StackOverflowError(BaseException):
    pass


if __name__ == "__main__":
    stack = Stack(10)
    for i in range(10):
        stack.push(i)

    assert stack.is_full()
    assert str(stack) == str([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])
    assert stack.pop() == 9
    assert stack.peek() == 8

    stack.push(100)
    assert str(stack) == str([0, 1, 2, 3, 4, 5, 6, 7, 8, 100])

    assert not stack.is_empty()
    assert stack.size() == 10

    num = 5
    assert num in stack
    num = 55
    assert num not in stack