code: func (t MicroTime) MarshalJSON() ([]byte, error) {
  	if t.IsZero() {
  		// Encode unset/nil objects as JSON's "null".
  		return []byte("null"), nil
  	}
  
  	return json.Marshal(t.UTC().Format(RFC3339Micro))
  }
docs: // MarshalJSON implements the json.Marshaler interface.