code: func findIconIcccm(X *xgbutil.XUtil, wid xproto.Window) (*Image, error) {
  	hints, err := icccm.WmHintsGet(X, wid)
  	if err != nil {
  		return nil, err
  	}
  
  	// Only continue if the WM_HINTS flags say an icon is specified and
  	// if at least one of icon pixmap or icon mask is non-zero.
  	if hints.Flags&icccm.HintIconPixmap == 0 ||
  		(hints.IconPixmap == 0 && hints.IconMask == 0) {
  
  		return nil, fmt.Errorf("No icon found in WM_HINTS.")
  	}
  
  	return NewIcccmIcon(X, hints.IconPixmap, hints.IconMask)
  }
docs: // findIconIcccm helps FindIcon by trying to return an icccm-style icon.