code: def is_subnet_source_fw(cls, tenant_id, subnet):
          
          cfg = config.CiscoDFAConfig().cfg
          subnet = subnet.split('/')[0]
          in_sub_dict = cls.get_in_ip_addr(tenant_id)
          if not in_sub_dict:
              return False
          if in_sub_dict.get('subnet') == subnet:
              return True
          out_sub_dict = cls.get_out_ip_addr(tenant_id)
          if not out_sub_dict:
              return False
          if out_sub_dict.get('subnet') == subnet:
              return True
          dummy_sub = cfg.firewall.fw_service_dummy_ip_subnet
          dummy_sub = dummy_sub.split('/')[0]
          return subnet == dummy_sub
docs: Check if the subnet is created as a result of any FW operation.