Code Sketch

clear()
def shape(len: Int) {
    repeat(2) {
        right(90, len)
        right()
    }
}

setSpeed(fast)
setBackground(Color(0, 0, 0))
setPenThickness(2)

//val colors = ArrayBuffer(red, blue, green, cyan, yellow)

repeatFor(rangeTo(1, 10)) { e =>
    repeatFor(rangeTo(1, 40)) { e =>
        //val idx = e % 5
        //val myColor = colors(idx)
        setPenColor(cm.hsl(e*357, 1, 0.5))
        shape(e * 5 + 10)
        right(1)
    }
    left(40)
    right(36)
}
invisible()