code: func (d Data) GetAndUnmarshalJSON(key string, v interface{}) error {
  	if err := json.Unmarshal([]byte(d.Get(key)), v); err != nil {
  		return err
  	}
  	return nil
  }
docs: // GetAndUnmarshalJSON assumes that the first element in data[key] is a json string and
  // attempts to unmarshal it into v. If unmarshaling was not successful, returns an error.
  // v should be a pointer to some data structure.