code: def horizontal_path(size):
      
      width, height = size
      return (((x, y) for x in range(width)) for y in range(height))
docs: Creates a generator for progressing horizontally through an image.
      :param size: A tuple (width, height) of the image size
      :return: A generator that yields a set of rows through the image.
      Each row is a generator that yields pixel coordinates.