n = -7 (slider from -10 to 10, step 1)
l1 = Flatten(Sequence[Sequence[Segment[(j, k, 0), (j + k, (j * k), 10)], j, n, n], k, -20, 20])
l2 = Flatten(Sequence[Sequence[(j + k, (j * k), 10), j, n, n], k, -20, 20])