{"ast_node_type":"variable","tokens":[{"end":96,"kind":"keyword","start":0,"text":"let"}]}
                    let mut mode = ImplTraitReplacingMode::ReturnPosition(FxHashSet::default());
                    let fn_placeholders = TyBuilder::placeholder_subst(self.db, func);
                    let result = self.insert_inference_vars_for_impl_trait(