code: func (a *APIDefinition) IterateResponses(it ResponseIterator) error {
  	names := make([]string, len(a.Responses))
  	i := 0
  	for n := range a.Responses {
  		names[i] = n
  		i++
  	}
  	sort.Strings(names)
  	for _, n := range names {
  		if err := it(a.Responses[n]); err != nil {
  			return err
  		}
  	}
  	return nil
  }
docs: // IterateResponses calls the given iterator passing in each response sorted in alphabetical order.
  // Iteration stops if an iterator returns an error and in this case IterateResponses returns that
  // error.