code: func (db *DB) checkMeta() (bool, error) {
  	var version []byte
  	err := db.db.Update(func(tx *bolt.Tx) error {
  		meta, err := tx.CreateBucketIfNotExists([]byte("meta"))
  		if err != nil {
  			return err
  		}
  
  		version = meta.Get([]byte("version"))
  		if version != nil {
  			return nil
  		}
  
  		err = meta.Put([]byte("version"), schemaVersion)
  		if err != nil {
  			return err
  		}
  		version = schemaVersion
  		return nil
  	})
  
  	return bytes.Equal(version, schemaVersion), err
  }
docs: // checkMeta check's the db's metadata, ensuring the version of the db is
  // correct, or setting it if it does not exist.