{"ast_node_type":"other","tokens":[{"end":71,"kind":"keyword","start":0,"text":"rustc_parse_format::ArgumentIs(idx)"}]}
                                    rustc_parse_format::ArgumentIs(idx)
                                let (operand_idx, _name) = match arg.position {
                                    | rustc_parse_format::ArgumentImplicitlyIs(idx) => {