bc1d5164 ​

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