code: func newLdbCacheIter(snap *dbCacheSnapshot, slice *util.Range) *ldbCacheIter {
  	iter := snap.pendingKeys.Iterator(slice.Start, slice.Limit)
  	return &ldbCacheIter{Iterator: iter}
  }
docs: // newLdbCacheIter creates a new treap iterator for the given slice against the
  // pending keys for the passed cache snapshot and returns it wrapped in an
  // ldbCacheIter so it can be used as a leveldb iterator.