def METHOD_NAME(self, extra: dict | None = None) -> ExchangeObject:
    """
    Get current local weights or weight differences.
    Args:
        extra: Dict with additional information that can be provided by the FL system.
    Returns:
        ExchangeObject: current local weights or weight differences.
    `ExchangeObject` example:
    .. code-block:: python
        ExchangeObject(
            weights = self.trainer.network.state_dict(),
            optim = None,  # could be self.optimizer.state_dict()
            weight_type = WeightType.WEIGHTS
        )
    """
    raise NotImplementedError(f"Subclass {self.__class__.__name__} must implement this method.")