def fringe8(xxx_todo_changeme, xxx_todo_changeme1):
    (px, py) = xxx_todo_changeme
    (x1, y1, x2, y2) = xxx_todo_changeme1
    nonzero = (pair for pair in product((-1, 0, 1), (-1, 0, 1)) if pair !=
        (0, 0))
How can this verbose, unpythonic routine be improved?