code: func (ml MetalLayer) PixelFormat() mtl.PixelFormat {
  	return mtl.PixelFormat(C.MetalLayer_PixelFormat(ml.metalLayer))
  }
docs: // PixelFormat returns the pixel format of textures for rendering layer content.
  //
  // Reference: https://developer.apple.com/documentation/quartzcore/cametallayer/1478155-pixelformat.