code: def fetch_sampling_target(self, rules):
          
          now = int(time.time())
          report_docs = self._generate_reporting_docs(rules, now)
          resp = self._xray_client.get_sampling_targets(
              SamplingStatisticsDocuments=report_docs
          )
          new_docs = resp['SamplingTargetDocuments']
  
          targets_mapping = {}
          for doc in new_docs:
              TTL = self._dt_to_epoch(doc['ReservoirQuotaTTL']) if doc.get('ReservoirQuotaTTL', None) else None
              target = {
                  'rate': doc['FixedRate'],
                  'quota': doc.get('ReservoirQuota', None),
                  'TTL': TTL,
                  'interval': doc.get('Interval', None),
              }
              targets_mapping[doc['RuleName']] = target
  
          return targets_mapping, self._dt_to_epoch(resp['LastRuleModification'])
docs: Report the current statistics of sampling rules and
          get back the new assgiend quota/TTL froom the X-Ray service.
          The call is proxied and signed via X-Ray Daemon.