Get metrics on producer performance.

        This is ported from the Java Producer, for details see:
        https://kafka.apache.org/documentation/#producer_monitoring

        Warning:
            This is an unstable interface. It may change in future
            releases without warning.

def metrics(self, raw=False):
        """Get metrics on producer performance.

        This is ported from the Java Producer, for details see:
        https://kafka.apache.org/documentation/#producer_monitoring

        Warning:
            This is an unstable interface. It may change in future
            releases without warning.
        """
        if raw:
            return self._metrics.metrics.copy()

        metrics = {}
        for k, v in six.iteritems(self._metrics.metrics.copy()):
            if k.group not in metrics:
                metrics[k.group] = {}
            if k.name not in metrics[k.group]:
                metrics[k.group][k.name] = {}
            metrics[k.group][k.name] = v.value()
        return metrics