54d82841 ​

input = fill #0 (fill #1 black) |> fold rect #2
output = fill #0 (fill #1 black) |> fold (fold rect) #3
(VInt, HInt, UList ((VInt, HInt, VInt, HInt), Color), OList UList ((VInt, HInt, VInt, HInt), Color))
(8v, 8h, {((3v, 8h, 4v, 8h), fuschia), ((3v, 6h, 3v, 8h), fuschia), ((3v, 6h, 4v, 6h), fuschia), ((1v, 4h, 2v, 4h), fuschia), ((1v, 2h, 1v, 4h), fuschia), ((1v, 2h, 2v, 2h), fuschia)}, [{((3v, 8h, 4v, 8h), fuschia), ((3v, 6h, 3v, 8h), fuschia), ((3v, 6h, 4v, 6h), fuschia), ((1v, 4h, 2v, 4h), fuschia), ((1v, 2h, 1v, 4h), fuschia), ((1v, 2h, 2v, 2h), fuschia), ((8v, 7h, 8v, 7h), yellow), ((8v, 3h, 8v, 3h), yellow)}])
(5v, 5h, {((1v, 4h, 2v, 4h), green), ((1v, 2h, 1v, 4h), green), ((1v, 2h, 2v, 2h), green)}, [{((1v, 4h, 2v, 4h), green), ((1v, 2h, 1v, 4h), green), ((1v, 2h, 2v, 2h), green), ((5v, 3h, 5v, 3h), yellow)}])
(5v, 7h, {((3v, 7h, 4v, 7h), fuschia), ((3v, 5h, 3v, 7h), fuschia), ((3v, 5h, 4v, 5h), fuschia), ((2v, 4h, 3v, 4h), teal), ((2v, 2h, 2v, 4h), teal), ((2v, 2h, 3v, 2h), teal)}, [{((3v, 5h, 4v, 7h), fuschia)}, {((2v, 4h, 3v, 4h), teal), ((2v, 2h, 2v, 4h), teal), ((2v, 2h, 3v, 2h), teal), ((5v, 7h, 5v, 7h), black), ((5v, 6h, 5v, 6h), yellow), ((5v, 3h, 5v, 3h), yellow), ((4v, 6h, 4v, 6h), black)}])
(7v, 11h, {((3v, 11h, 4v, 11h), green), ((3v, 9h, 3v, 11h), green), ((3v, 9h, 4v, 9h), green), ((1v, 4h, 2v, 4h), grey), ((1v, 2h, 1v, 4h), grey), ((1v, 2h, 2v, 2h), grey), ((2v, 8h, 3v, 8h), teal), ((2v, 6h, 2v, 8h), teal), ((2v, 6h, 3v, 6h), teal)}, ?)