code: func (db *Database) Get(key []byte) ([]byte, error) {
  	db.lock.RLock()
  	defer db.lock.RUnlock()
  
  	if db.db == nil {
  		return nil, errMemorydbClosed
  	}
  	if entry, ok := db.db[string(key)]; ok {
  		return common.CopyBytes(entry), nil
  	}
  	return nil, errMemorydbNotFound
  }
docs: // Get retrieves the given key if it's present in the key-value store.