code: func (s *LDBStore) Has(_ context.Context, addr Address) bool {
  	s.lock.RLock()
  	defer s.lock.RUnlock()
  
  	ikey := getIndexKey(addr)
  	_, err := s.db.Get(ikey)
  
  	return err == nil
  }
docs: // Has queries the underlying DB if a chunk with the given address is stored
  // Returns true if the chunk is found, false if not