code: func (order *TermsOrder) Source() (interface{}, error) {
  	source := make(map[string]string)
  	if order.Ascending {
  		source[order.Field] = "asc"
  	} else {
  		source[order.Field] = "desc"
  	}
  	return source, nil
  }
docs: // Source returns serializable JSON of the TermsOrder.