code: func ReadConfigFile(filename string, out interface{}) error {
  	configData, err := ioutil.ReadFile(filename)
  	if err != nil {
  		return err
  	}
  	return json.Unmarshal(configData, out)
  }
docs: // ReadConfigFile takes a file path as an argument and attempts to
  // unmarshal the content of the file into a struct containing a
  // configuration of a boulder component.