code: func (r Rect) Union(s Rect) Rect {
  	return R(
  		math.Min(r.Min.X, s.Min.X),
  		math.Min(r.Min.Y, s.Min.Y),
  		math.Max(r.Max.X, s.Max.X),
  		math.Max(r.Max.Y, s.Max.Y),
  	)
  }
docs: // Union returns the minimal Rect which covers both r and s. Rects r and s must be normalized.