code: func (s *Sprite) Draw(screen *ebiten.Image, dx, dy int, alpha float64) {
  	op := &ebiten.DrawImageOptions{}
  	op.GeoM.Translate(float64(s.x+dx), float64(s.y+dy))
  	op.ColorM.Scale(1, 1, 1, alpha)
  	screen.DrawImage(s.image, op)
  	screen.DrawImage(s.image, op)
  }
docs: // Draw draws the sprite.