code: func (f *Fpdf) ClipEnd() {
  	if f.err == nil {
  		if f.clipNest > 0 {
  			f.clipNest--
  			f.out("Q")
  		} else {
  			f.err = fmt.Errorf("error attempting to end clip operation out of sequence")
  		}
  	}
  }
docs: // ClipEnd ends a clipping operation that was started with a call to
  // ClipRect(), ClipRoundedRect(), ClipText(), ClipEllipse(), ClipCircle() or
  // ClipPolygon(). Clipping operations can be nested. The document cannot be
  // successfully output while a clipping operation is active.
  //
  // The ClipText() example demonstrates this method.