code: func (c *Config) UpdateFromFile(path string) error {
  	data, err := ioutil.ReadFile(path)
  	if err != nil {
  		return err
  	}
  
  	t := new(tomlConfig)
  	t.fromConfig(c)
  
  	_, err = toml.Decode(string(data), t)
  	if err != nil {
  		return fmt.Errorf("unable to decode configuration %v: %v", path, err)
  	}
  
  	t.toConfig(c)
  	return nil
  }
docs: // UpdateFromFile populates the Config from the TOML-encoded file at the given path.
  // Returns errors encountered when reading or parsing the files, or nil
  // otherwise.