to shadesofyellow
  repeat 255 [
    setpc (se 255-repcount 255-repcount 0)
    circle 255 - repcount
  ]
end

to rainbow
; red, orange, yellow, green, blue
  rt 90
  repeat 255 [
    setpc (se 255 repcount 0)
    arc 180 20+255+(255-repcount)
  ]
  repeat 255 [
    setpc (se 255-repcount 255 0)
    arc 180 20+(255-repcount)
  ]
end