code: func BlendBGRA(dest, src BGRA) BGRA {
  	alpha := float64(src.A) / 255.0
  	return BGRA{
  		B: blend(dest.B, src.B, alpha),
  		G: blend(dest.G, src.G, alpha),
  		R: blend(dest.R, src.R, alpha),
  		A: 0xff,
  	}
  }
docs: // Blend returns the blended alpha color for src and dest colors.
  // This assumes that the destination has alpha = 1.