code: func cacheAtom(xu *xgbutil.XUtil, name string, aid xproto.Atom) {
  	xu.AtomsLck.Lock()
  	xu.AtomNamesLck.Lock()
  	defer xu.AtomsLck.Unlock()
  	defer xu.AtomNamesLck.Unlock()
  
  	xu.Atoms[name] = aid
  	xu.AtomNames[aid] = name
  }
docs: // cacheAtom puts an atom into the cache.