    def clear(self) -> None:
        """Remove all labelsets from the metric"""
        if 'prometheus_multiproc_dir' in os.environ or 'PROMETHEUS_MULTIPROC_DIR' in os.environ:
            warnings.warn(
                "Clearing labels has not been implemented in multi-process mode yet",
                UserWarning)
        with self._lock:
            self._metrics = {}
Remove all labelsets from the metric
prometheus_client/metrics.py