623ea044 ​

let n: Int
let y: Int
let x: Int
let c: Color

let input = fill n (fill n black)
  |> point (y, x) c

let output = fill n (fill n black)
  |> rep2 (1, 1) [(y, x, c)]
  |> rep2 (1, -1) [(y, x, c)]