0934a4d8 ​

let g: OList OList Color
let r: (Int, Int, Int, Int)

let input = g
  |> λg. flat [g, rev g]
  |> λg. hcat [g, map rev g]
  |> gtake (1, 1, 30, 30)
  |> rect (r, teal)

let output = g
  |> λg. flat [g, rev g]
  |> λg. hcat [g, map rev g]
  |> gtake (1, 1, 30, 30)
  |> gtake r