main.py

def for_each(iterable, function):
    running = True
    while running:
        try:
            a = next(iterable)
            function(a)
        except StopIteration:
            running = False

def length(array):
    length = 0
    iterable = iter(array)
    while array:
        try:
            next(iterable)
            length += 1
        except StopIteration:
            pass
    return length

if __name__ == '__main__':
    a = iter([1,2,3,4])
    for_each(a, print)
    print(length(a) == len(a))