{"ast_node_type":"variable","tokens":[{"end":45,"kind":"keyword","start":0,"text":"let"}]}
        let index_fn_op = Operand::const_zst(
        let mut result: Place = self.temp(result_ref, current, span)?.into();
            TyKind::FnDef(CallableDefId::FunctionId(index_fn.0).to_chalk(self.db), index_fn.1)