code: func Rotate(dst draw.Image, src image.Image, opt *RotateOptions) error {
  	if dst == nil {
  		return errors.New("graphics: dst is nil")
  	}
  	if src == nil {
  		return errors.New("graphics: src is nil")
  	}
  
  	angle := 0.0
  	if opt != nil {
  		angle = opt.Angle
  	}
  
  	return I.Rotate(angle).TransformCenter(dst, src, interp.Bilinear)
  }
docs: // Rotate produces a rotated version of src, drawn onto dst.