fn cube = (length, center) => {
  let l = length/2
  let x = center[0]
  let y = center[1]
  let p0 = [-l + x, -l + y]
  let p1 = [-l + x,  l + y]
  let p2 = [ l + x,  l + y]
  let p3 = [ l + x, -l + y]

  return startSketchAt(p0)
  |> lineTo(p1, %)
  |> lineTo(p2, %)
  |> lineTo(p3, %)
  |> lineTo(p0, %)
  |> close(%)
  |> extrude(length, %)
}

const myCube = cube(40, [0,0])