{"ast_node_type":"variable","tokens":[{"end":87,"kind":"keyword","start":0,"text":"let"}]}
                        let base_ty = Ty::new_adt(self.infcx.tcx, *adt, identity_args);
                            GenericArgs::identity_for_item(self.infcx.tcx, adt.did());
                        let base_generic_arg = identity_args[param_index as usize];