docs: def access_level_up_to(self, access_level):
          """ returns all items that have an access level equal or lower than the one specified """
          # if access_level is number
          if isinstance(access_level, int):
              value = access_level
          # else if is string get the numeric value
          else:
              value = ACCESS_LEVELS.get(access_level)
          # return queryset
          return self.filter(access_level__lte=value)