docs: def get_or_save_default(self, key, default_value):
          """
          Get value stored in cache file or store there default value.
          :param key:
          :param default_value:
          :return:
          """
          val = self.get_or_none(key)
          if val is None:
              self.update(key, default_value)
              val = default_value
          return val