8), 'ExplainedVariance': tensor(-0.8969)}
        current stats={'MeanSquaredError': tensor(2.0268), 'ExplainedVariance': tensor(-1.0206)}
        current stats={'MeanSquaredError': tensor(1.9491), 'ExplainedVariance': tensor(-0.8298)}
        current stats={'MeanSquaredError': tensor(1.9800), 'ExplainedVariance': tensor(-0.9199)}
        current stats={'MeanSquaredError': tensor(2.2481), 'ExplainedVariance': tensor(-1.1622)}
        >>> from pprint import pprint
        >>> best_res, which_epoch = tracker.best_metric(return_step=True)
        >>> pprint(best_res)  # doctest: +ELLIPSIS
        {'ExplainedVariance': -0.829...,
         'MeanSquaredError': 1.821...}
        >>> which_epoch
        {'MeanSquaredError': 0, 'ExplainedVariance': 2}
        >>> pprint(tracker.compute_all())
        {'ExplainedVariance': tensor([-0.8969, -1.0206, -0.8298, -0.9199, -1.1622]),
         'MeanSquaredError': tensor([1.8218, 2.0268, 1.9491, 1.9800, 2.2481])}

    T