code: boolean delete() {
              Node<E> b = getPrev();
              Node<E> f = getNext();
              if (b != null && f != null && !f.isMarker() &&
                  casNext(f, new Node<E>(f))) {
                  if (b.casNext(this, f))
                      f.setPrev(b);
                  return true;
              }
              return false;
          }
docs: Tries to mark this node as deleted, failing if already
  deleted or if this node is header or trailer.
  
  @return true if successful