def negative(picButterfly2):
    for px in getPixels(picButterfly1):
        red=getRed(px)
        green=getGreen(px)
        blue=getBlue(px)
        negColor=makeColor(255-red, 255-green, 255-blue)
        setColor(px,negColor)

def negative(picButterfly1):
   for px in getPixels(picButterfly1):
      red=getRed(px)
      green=getGreen(px)
      blue=getBlue(px)
      negColor=makeColor(255-red, 255-green, 255-blue)
      setColor(px,negColor)

file = pickAFile()
picture = makePicture(file)

negative(picture)
show(picture)