<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def convert_fwdb_event_msg(self, rule, tenant_id, rule_id, policy_id):
 """Convert the Firewall DB to a event message format. From inputs from DB, this will create a FW rule dictionary that resembles the actual data from Openstack when a rule is created. This is usually called after restart, in order to populate local cache. """

        rule.update({'tenant_id': tenant_id, 'id': rule_id,
                     'firewall_policy_id': policy_id})
        fw_rule_data = {'firewall_rule': rule}
        return fw_rule_data