code: func NewWithFile(path string) (*Database, error) {
  	db := &Database{make(map[string]string), make(map[string]string), path}
  	db.customPath = path
  
  	blob, err := Asset("4byte.json")
  	if err != nil {
  		return nil, err
  	}
  	if err := json.Unmarshal(blob, &db.embedded); err != nil {
  		return nil, err
  	}
  	// Custom file may not exist. Will be created during save, if needed.
  	if _, err := os.Stat(path); err == nil {
  		if blob, err = ioutil.ReadFile(path); err != nil {
  			return nil, err
  		}
  		if err := json.Unmarshal(blob, &db.custom); err != nil {
  			return nil, err
  		}
  	}
  	return db, nil
  }
docs: // NewWithFile loads both the standard signature database (embedded resource
  // file) as well as a custom database. The latter will be used to write new
  // values into if they are submitted via the API.