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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 create_os_dummy_rtr(self, tenant_id, fw_dict, is_fw_virt=False):
 """Create the dummy interface and attach it to router. Attach the dummy interface to the Openstack router and store the info in DB. """

        res = fw_const.OS_DUMMY_RTR_CREATE_SUCCESS
        tenant_name = fw_dict.get('tenant_name')
        try:
            rtr_id = fw_dict.get('router_id')
            if rtr_id is None:
                LOG.error("Invalid router id, attaching dummy interface"
                          " failed")
                return False
            if is_fw_virt:
                net_id = subnet_id = None
            else:
                net_id, subnet_id = (
                    self._attach_dummy_intf_rtr(tenant_id, tenant_name,
                                                rtr_id))
                if net_id is None or subnet_id is None:
                    LOG.error("Invalid net_id or subnet_id, creating dummy"
                              " interface failed")
                    return False
        except Exception as exc:
            # Function _attach_dummy_intf_rtr already took care of
            # cleanup for error cases.
            LOG.error("Creation of Openstack Router failed "
                      "tenant %(tenant)s, Exception %(exc)s",
                      {'tenant': tenant_id, 'exc': str(exc)})
            res = fw_const.OS_DUMMY_RTR_CREATE_FAIL
        self.store_fw_db_router(tenant_id, net_id, subnet_id, rtr_id, res)
        return True