code: func (t *TagMap) MarshalJSON() ([]byte, error) {
  	m := make(map[string]string, len(*t))
  	if len(*t) > 0 {
  		for k, v := range *t {
  			m[k] = v
  		}
  	}
  	return json.Marshal(m)
  }
docs: // MarshalJSON implements the json.Marshaler interface.