docs: def format_active_subjects(request):
      """Create a string listing active subjects for this connection, suitable for
      appending to authentication error messages."""
      decorated_subject_list = [request.primary_subject_str + ' (primary)']
      for subject in request.all_subjects_set:
          if subject != request.primary_subject_str:
              decorated_subject_list.append(subject)
      return ', '.join(decorated_subject_list)