928ad970 ​

input = fill #0 (fill #1 black) |> rect ((#4.1 - 1, #4.2 - 1, #4.3 + 1, #4.4 + 1), #2) |> fold (λr. rect ((r.1, r.2, r.1, r.2), grey)) #3 |> rect (#4, black)
output = fill #0 (fill #1 black) |> fold (fold rect) #5
(VInt, HInt, Color, UList (VInt, HInt), (VInt, HInt, VInt, HInt), OList UList ((VInt, HInt, VInt, HInt), Color))
(12v, 13h, blue, {(12v, 5h), (7v, 12h), (7v, 2h), (2v, 5h)}, (6v, 7h, 7v, 7h), [{((3v, 3h, 11v, 11h), blue)}, {((4v, 4h, 10v, 10h), black)}, {((5v, 6h, 8v, 8h), blue)}, {((12v, 5h, 12v, 5h), grey), ((7v, 12h, 7v, 12h), grey), ((7v, 2h, 7v, 2h), grey), ((2v, 5h, 2v, 5h), grey), ((6v, 7h, 7v, 7h), black)}])
(15v, 13h, green, {(13v, 6h), (9v, 11h), (6v, 2h), (2v, 6h)}, (7v, 6h, 7v, 6h), [{((3v, 3h, 12v, 10h), green)}, {((4v, 4h, 11v, 9h), black)}, {((6v, 5h, 8v, 7h), green)}, {((13v, 6h, 13v, 6h), grey), ((9v, 11h, 9v, 11h), grey), ((6v, 2h, 6v, 2h), grey), ((2v, 6h, 2v, 6h), grey), ((7v, 6h, 7v, 6h), black)}])
(15v, 14h, yellow, {(14v, 8h), (9v, 2h), (7v, 13h), (3v, 7h)}, (7v, 6h, 8v, 7h), [{((4v, 3h, 13v, 12h), yellow)}, {((5v, 4h, 12v, 11h), black)}, {((6v, 5h, 9v, 8h), yellow)}, {((14v, 8h, 14v, 8h), grey), ((9v, 2h, 9v, 2h), grey), ((7v, 13h, 7v, 13h), grey), ((3v, 7h, 3v, 7h), grey), ((7v, 6h, 8v, 7h), black)}])
(15v, 15h, teal, {(14v, 6h), (10v, 13h), (7v, 3h), (2v, 8h)}, (7v, 7h, 7v, 8h), ?)