code: func JSONHandler(front string) (map[string]interface{}, error) {
  	var rst interface{}
  	err := json.Unmarshal([]byte(front), &rst)
  	if err != nil {
  		return nil, err
  	}
  	return rst.(map[string]interface{}), nil
  }
docs: //JSONHandler implements HandlerFunc interface. It extracts front matter data from the given
  // string argument by interpreting it as a json string.