chunk_fill('ABCDEFG', 3, 'x') --> ABC DEF Gxx

def chunk_fill(iterable, size, fillvalue=None):
    """
    chunk_fill('ABCDEFG', 3, 'x') --> ABC DEF Gxx
    """
    # TODO: not used
    args = [iter(iterable)] * size
    return itertools.zip_longest(*args, fillvalue=fillvalue)