docs: public @Nullable LabelAtom getLabelAtom(@CheckForNull String name) {
          if (name==null)  return null;
  
          while(true) {
              Label l = labels.get(name);
              if(l!=null)
                  return (LabelAtom)l;
  
              // non-existent
              LabelAtom la = new LabelAtom(name);
              if (labels.putIfAbsent(name, la)==null)
                  la.load();
          }
      }