code: func (c RGBA) Mul(d RGBA) RGBA {
  	return RGBA{
  		R: c.R * d.R,
  		G: c.G * d.G,
  		B: c.B * d.B,
  		A: c.A * d.A,
  	}
  }
docs: // Mul multiplies color c by color d component-wise (the components are not clamped).