code: func (iter *dbCacheIterator) Release() {
  	if !iter.released {
  		iter.dbIter.Release()
  		iter.cacheIter.Release()
  		iter.currentIter = nil
  		iter.released = true
  	}
  }
docs: // Release releases the iterator by removing the underlying treap iterator from
  // the list of active iterators against the pending keys treap.
  //
  // This is part of the leveldb iterator.Iterator interface implementation.