8597cfd7 ​

input = fill #0 (fill 9h black) |> fold rect #1
output = fill 2v (fill 2h #2)
(VInt, UList ((VInt, HInt, VInt, HInt), Color), Color)
(9v, {((6v, 7h, 9v, 7h), yellow), ((5v, 1h, 5v, 9h), grey), ((1v, 7h, 2v, 7h), yellow), ((1v, 3h, 1v, 3h), red), ((6v, 3h, 7v, 3h), red)}, yellow)
(9v, {((6v, 7h, 9v, 7h), yellow), ((6v, 3h, 9v, 3h), red), ((5v, 1h, 5v, 9h), grey), ((1v, 7h, 2v, 7h), yellow), ((1v, 3h, 1v, 3h), red)}, red)
(11v, {((7v, 7h, 11v, 7h), yellow), ((6v, 1h, 6v, 9h), grey), ((1v, 7h, 3v, 7h), yellow), ((1v, 3h, 1v, 3h), red), ((7v, 3h, 10v, 3h), red)}, red)
(11v, {((6v, 1h, 6v, 9h), grey), ((1v, 7h, 2v, 7h), yellow), ((1v, 3h, 2v, 3h), red), ((7v, 7h, 9v, 7h), yellow), ((7v, 3h, 10v, 3h), red)}, red)
(11v, {((6v, 1h, 6v, 9h), grey), ((1v, 7h, 2v, 7h), yellow), ((1v, 3h, 3v, 3h), red), ((7v, 7h, 10v, 7h), yellow), ((7v, 3h, 10v, 3h), red)}, ?)