{"ast_node_type":"variable","tokens":[{"end":98,"kind":"keyword","start":0,"text":"let"}]}
        let text = "{\"jsonrpc\": \"2.0\",\"id\": 3,\"method\": \"shutdown\", \"params\": null }";
    fn shutdown_with_explicit_null() {
        let msg: Message = serde_json::from_str(text).unwrap();