code: def Start(self):
      
      cron_jobs_ttl = config.CONFIG["DataRetention.cron_jobs_flows_ttl"]
      if not cron_jobs_ttl:
        self.Log("TTL not set - nothing to do...")
        return
  
      manager = aff4_cronjobs.GetCronManager()
      cutoff_timestamp = rdfvalue.RDFDatetime.Now() - cron_jobs_ttl
      if data_store.RelationalDBEnabled():
        deletion_count = manager.DeleteOldRuns(cutoff_timestamp=cutoff_timestamp)
  
      else:
        deletion_count = 0
        for job in manager.ReadJobs(token=self.token):
          deletion_count += manager.DeleteOldRuns(
              job, cutoff_timestamp=cutoff_timestamp, token=self.token)
          self.HeartBeat()
  
      self.Log("Deleted %d cron job runs." % deletion_count)
docs: Cleans up old cron job data.