iterators-8.py

class MyList:
    def __init__(self, iterable):
        self.items = iterable

    def __iter__(self):
        print(f"Calling __iter__ in MyList")
        return MyListIterator(self.items)

class MyListIterator:
    def __init__(self, iterable):
        self.items = iterable
        self.index = 0

    def __iter__(self):
        print("Only called when iterating over iterator itself")
        return self

    def __next__(self):
        if self.index < len(self.items):
            item = self.items[self.index]
            self.index += 1
            return item
        else:
            raise StopIteration
            

numbers = MyList([2, 5, 10, 3, 99, 42])
for number in numbers:
    for another_number in numbers:
        print(f"Outer: {number} | Inner: {another_number}")