def create_intervals(data):
    """
        Create a list of intervals out of set of ints.
    """
    results = []
    data = sorted(data)
    start = None
    current_number = None
    for number in data:
        if start is None:
            start = number
            current_number = start
            continue
        if number != start and number != (current_number + 1):
            results.append((start, current_number))
            start = number
        current_number = number
    if start is not None:
        results.append((start, current_number))
    return iter(results)


if __name__ == '__main__':
    # These "asserts" using only for self-checking and not necessary for auto-testing
    res = create_intervals(iter(sorted(list({1, 2, 3, 4, 5, 7, 8, 12}))))
    assert hasattr(res, '__iter__'), "your function should return the iterator object"
    assert hasattr(res, '__next__'), "your function should return the iterator object"

    assert list(create_intervals(iter(sorted(list({1, 2, 3, 4, 5, 7, 8, 12}))))) == [
        (1, 5), (7, 8), (12, 12)], "First"
    assert list(create_intervals(iter(sorted(list({1, 2, 3, 6, 7, 8, 4, 5}))))) == [
        (1, 8)], "Second"
    assert list(create_intervals(iter([]))) == [], "Empty"
    print('Almost done! The only thing left to do is to Check it!')