code: func b16(img *image.Paletted, x, y, size float64, angle int) {
  	points := pool.Get().([]float64)[:0]
  	m := size / 2
  	drawBlock(img, x, y, size, angle, append(points,
  		x+m, y,
  		x+size, y+m,
  		x, y+m,
  		x+m, y,
  	))
  
  	drawBlock(img, x, y, size, angle, append(points[:0],
  		x+m, y+m,
  		x+size, y+size,
  		x, y+size,
  		x+m, y+m,
  	))
  
  	pool.Put(points)
  }
docs: // b16
  //
  //  ---------
  //  |   #   |
  //  | ##### |
  //  |#######|
  //  |   #   |
  //  | ##### |
  //  |#######|
  //  ---------