code: func (r Rectangle) Inset(n float32) Rectangle {
  	if r.Dx() < 2*n {
  		r.Min[0] = (r.Min[0] + r.Max[0]) / 2
  		r.Max[0] = r.Min[0]
  	} else {
  		r.Min[0] += n
  		r.Max[0] -= n
  	}
  	if r.Dy() < 2*n {
  		r.Min[1] = (r.Min[1] + r.Max[1]) / 2
  		r.Max[1] = r.Min[1]
  	} else {
  		r.Min[1] += n
  		r.Max[1] -= n
  	}
  	return r
  }
docs: // Inset returns the rectangle r inset by n, which may be negative. If either
  // of r's dimensions is less than 2*n then an empty rectangle near the center
  // of r will be returned.