def v3_multimax(iterable):
    """Return a list of all maximum values.

    Bonus 1: make sure our function returned an empty list when
    given an empty iterable.
    """
    max_item = None
    for item in iterable:
        if max_item is None or item > max_item:
            max_item = item
    return [
        item
        for item in iterable
        if item == max_item
    ]