cb227835 ​

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