code: func StringToWaitDurationHookFunc() mapstructure.DecodeHookFunc {
  	return func(
  		f reflect.Type,
  		t reflect.Type,
  		data interface{}) (interface{}, error) {
  		if f.Kind() != reflect.String {
  			return data, nil
  		}
  		if t != reflect.TypeOf(WaitConfig{}) {
  			return data, nil
  		}
  
  		// Convert it by parsing
  		return ParseWaitConfig(data.(string))
  	}
  }
docs: // StringToWaitDurationHookFunc returns a function that converts strings to wait
  // value. This is designed to be used with mapstructure for parsing out a wait
  // value.