code: func (db *DB) Get(id *identity.ID, env envelope.Envelope) error {
  	return db.db.View(func(tx *bolt.Tx) error {
  		bucket := tx.Bucket([]byte{id.Type()})
  		if bucket == nil {
  			return errors.New("ID not found")
  		}
  
  		b := bucket.Get(id[:])
  		if b == nil {
  			return errors.New("ID not found")
  		}
  
  		return json.Unmarshal(b, env)
  	})
  }
docs: // Get returns the value of id in env. It returns an error if id does not exist.