<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def system_update_column_family(self, cf_def):
 """ updates properties of a column family. returns the new schema id. Parameters: - cf_def """

    self._seqid += 1
    d = self._reqs[self._seqid] = defer.Deferred()
    self.send_system_update_column_family(cf_def)
    return d