code: public void removeLL() {
      if (head[0] == this)
        head[0] = nextTag;
      if (prevTag != null) {
        prevTag.nextTag = nextTag;
      }
      if (nextTag != null) {
        nextTag.prevTag = prevTag;
      }
    }
docs: Removes this tag from the chain, connecting prevTag and nextTag. Does not
  modify "this" object's pointers, so the caller can refer to nextTag after
  removing it.