67a423a3 ​

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

let input = fill n (fill n black)
  |> vline (1, -1, x, vc)
  |> hline (y, 1, -1, hc)
  |> point (y, x) c

let output = fill n (fill n black)
  |> vline (1, -1, x, vc)
  |> hline (y, 1, -1, hc)
  |> rect ((y - 1, x - 1, y + 1, x + 1), yellow)
  |> point (y, x) c