def setPixelToBlack(pixel):
  for p in getPixels(pixel):
   value = getRed(p)
   setRed(p, value * 0)
   value = getGreen(p)
   setGreen(p, value * 0)
   value = getBlue(p)
   setBlue(p, value * 0)

def setPictureToBlack(picture):
  for p in getPixels(pixel):
    setPixelToBlack(pixel)

> f = pickAFile()
>>p = makePicture(f)
>>>setPictureToBlack(p)
>>>>explore(p), this should black out the image selected!