code: def _sum_values_by_context(metric, uid_from_labels):
          
          seen = {}
          for sample in metric.samples:
              uid = uid_from_labels(sample[OpenMetricsBaseCheck.SAMPLE_LABELS])
              if not uid:
                  # TODO
                  # metric.Clear()  # Ignore this metric message
                  continue
              # Sum the counter value accross all contexts
              if uid not in seen:
                  seen[uid] = sample
              else:
                  # We have to create a new tuple
                  seen[uid] = (
                      seen[uid][OpenMetricsBaseCheck.SAMPLE_NAME],
                      seen[uid][OpenMetricsBaseCheck.SAMPLE_LABELS],
                      seen[uid][OpenMetricsBaseCheck.SAMPLE_VALUE] + sample[OpenMetricsBaseCheck.SAMPLE_VALUE],
                  )
                  # TODO
                  # metric.Clear()  # Ignore this metric message
          return seen
docs: Iterates over all metrics in a metric and sums the values
          matching the same uid. Modifies the metric family in place.
          :param metric: prometheus metric family
          :param uid_from_labels: function mapping a metric.label to a unique context id
          :return: dict with uid as keys, metric object references as values