def circular_shifts(iterable):
    """Return a list of circular shifts of *iterable*.

        >>> circular_shifts(range(4))
        [(0, 1, 2, 3), (1, 2, 3, 0), (2, 3, 0, 1), (3, 0, 1, 2)]
    """
    lst = list(iterable)
    return take(len(lst), windowed(cycle(lst), len(lst)))