docs: def _get_cache_value(self, key, empty, type):
          """Used internally by the accessor properties."""
          if type is bool:
              return key in self
          if key in self:
              value = self[key]
              if value is None:
                  return empty
              elif type is not None:
                  try:
                      value = type(value)
                  except ValueError:
                      pass
              return value