def DeleteOldRuns(self, cutoff_timestamp=None):
    """Deletes runs that were started before the timestamp given."""
    if cutoff_timestamp is None:
      raise ValueError("cutoff_timestamp can't be None")

    return data_store.REL_DB.DeleteOldCronJobRuns(
        cutoff_timestamp=cutoff_timestamp)
Deletes runs that were started before the timestamp given.