code: func loadBlockDB() (database.DB, error) {
  	// The database name is based on the database type.
  	dbName := blockDbNamePrefix + "_" + cfg.DbType
  	dbPath := filepath.Join(cfg.DataDir, dbName)
  	fmt.Printf("Loading block database from '%s'\n", dbPath)
  	db, err := database.Open(cfg.DbType, dbPath, activeNetParams.Net)
  	if err != nil {
  		return nil, err
  	}
  	return db, nil
  }
docs: // loadBlockDB opens the block database and returns a handle to it.