code: def gauge(self, name, description, labels=None, **kwargs):
          
  
          return self._track(
              Gauge,
              lambda metric, time: metric.dec(),
              kwargs, name, description, labels,
              registry=self.registry,
              before=lambda metric: metric.inc()
          )
docs: Use a Gauge to track the number of invocations in progress
          for the method.
  
          :param name: the name of the metric
          :param description: the description of the metric
          :param labels: a dictionary of `{labelname: callable_or_value}` for labels
          :param kwargs: additional keyword arguments for creating the Gauge