Define a function named posterize. This function expects an image and a tuple of RGB values as arguments.

def posterize(image, tup):
  for row in range(image.height):
    for col in range(image.width):
      p = image.getPixel(col, row)
      newRed = tup[0]
      newGreen = tup[1]
      newBlue = tup[2]
      newpixel = image.Pixel(newRed, newGreen, newBlue)
      image.setPixel(col, row, newpixel)
  return image
    
posterize(image, (255, 0, 0))