List of metrics to track for this learning process

def metrics(self) -> list:
        """ List of metrics to track for this learning process """
        return [
            AveragingNamedMetric("policy_loss"),
            AveragingNamedMetric("value_loss"),
            AveragingNamedMetric("policy_entropy"),
            AveragingNamedMetric("approx_kl_divergence"),
            AveragingNamedMetric("clip_fraction"),
            AveragingNamedMetric("grad_norm"),
            AveragingNamedMetric("advantage_norm"),
            AveragingNamedMetric("explained_variance")
        ]