{"nftables": [{"metainfo": {"version": "VERSION", "release_name": "RELEASE_NAME", "json_schema_version": 1}}, {"table": {"family": "ip", "name": "t", "handle": 0}}, {"set": {"family": "ip", "name": "s", "table": "t", "type": ["ipv4_addr", "ifname"], "handle": 0, "flags": ["interval"], "elem": [{"concat": ["1.2.3.4", "foo"]}]}}]}