code: func (r Rect) Resized(anchor, size Vec) Rect {
  	if r.W()*r.H() == 0 {
  		panic(fmt.Errorf("(%T).Resize: zero area", r))
  	}
  	fraction := Vec{size.X / r.W(), size.Y / r.H()}
  	return Rect{
  		Min: anchor.Add(r.Min.Sub(anchor).ScaledXY(fraction)),
  		Max: anchor.Add(r.Max.Sub(anchor).ScaledXY(fraction)),
  	}
  }
docs: // Resized returns the Rect resized to the given size while keeping the position of the given
  // anchor.
  //
  //   r.Resized(r.Min, size)      // resizes while keeping the position of the lower-left corner
  //   r.Resized(r.Max, size)      // same with the top-right corner
  //   r.Resized(r.Center(), size) // resizes around the center
  //
  // This function does not make sense for resizing a rectangle of zero area and will panic. Use
  // ResizedMin in the case of zero area.