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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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