{"ast_node_type":"other","tokens":[{"end":89,"kind":"keyword","start":0,"text":".chain((0..untuple_arg.layout().fields.count()).map(|i|"}]}
                                .chain((0..untuple_arg.layout().fields.count()).map(|i| {
                                .map(|a| interp_ok(a.clone()))
                                    self.fn_arg_field(untuple_arg, FieldIdx::from_usize(i))