docs: def DeleteOldCronJobRuns(self, cutoff_timestamp):
      """Deletes cron job runs for a given job id."""
      deleted = 0
      for run in list(itervalues(self.cronjob_runs)):
        if run.timestamp < cutoff_timestamp:
          del self.cronjob_runs[(run.cron_job_id, run.run_id)]
          deleted += 1
  
      return deleted