code: def get_metric(self, timestamp):
          
          if not self.points:
              return None
  
          with self._points_lock:
              ts_list = get_timeseries_list(self.points, timestamp)
          return metric.Metric(self.descriptor, ts_list)
docs: Get a metric including all current time series.
  
          Get a :class:`opencensus.metrics.export.metric.Metric` with one
          :class:`opencensus.metrics.export.time_series.TimeSeries` for each
          set of label values with a recorded measurement. Each `TimeSeries`
          has a single point that represents the last recorded value.
  
          :type timestamp: :class:`datetime.datetime`
          :param timestamp: Recording time to report, usually the current time.
  
          :rtype: :class:`opencensus.metrics.export.metric.Metric` or None
          :return: A converted metric for all current measurements.