Destructive Stack Iteration

Question

This is my Stack implementation.

class Stack:
    def __init__(self):
        self.head = None
        self.size = 0

    def push(self, item):
        node          


        

Answer 1

Because you can have more than one iterator on the same stack, __iter__ has to return a iterator-object, that iterates the stack:

class Stack:
    def __init__(self):
        self.head = None
        self.size = 0

    def push(self, item):
        node = Node(item)
        if self.head:
            node.next = self.head
        self.head = node
        self.size += 1

    def pop(self):
        if self.size == 0:
            raise ValueError('Popping off an empty stack!')
        item = self.head.val
        self.head = self.head.next
        return item

    def peek(self):
        if self.size == 0:
            raise ValueError('Peeking into an empty stack!')
        return self.head.val

    def __iter__(self):
        return StackIterator(self.head)

class StackIterator:
    def __init__(self, head):
        self.head = head

    def __iter__(self):
        return self

    def __next__(self):
        if not self.head:
            raise StopIteration()
        item = self.head.val
        self.head = self.head.next
        return item