docs: def get_users_indexed_by_lang():
          """
          Return all the translator users indexed by lang
          :return:
          """
          result = {}
          users = TransUser.objects.filter(active=True).select_related('user')
          for user in users:
              for lang in user.languages.all():
                  if lang.code not in result:
                      result[lang.code] = set()
                  result[lang.code].add(user)
          return result