code: func (dbInst *DB) Close() {
  	dbInst.mux.Lock()
  	defer dbInst.mux.Unlock()
  	if dbInst.dbState == closed {
  		return
  	}
  	if err := dbInst.db.Close(); err != nil {
  		logger.Errorf("Error closing leveldb: %s", err)
  	}
  	dbInst.dbState = closed
  }
docs: // Close closes the underlying db