Return the id regex from the parameters

def _get_id_format(self):
        """ Return the id regex from the parameters"""
        id_format = gf.safe_get(
            self.parameters,
            gc.PPN_TASK_OS_FILE_ID_REGEX,
            self.DEFAULT_ID_FORMAT,
            can_return_none=False
        )
        try:
            identifier = id_format % 1
        except (TypeError, ValueError) as exc:
            self.log_exc(u"String '%s' is not a valid id format" % (id_format), exc, True, ValueError)
        return id_format