{"ast_node_type":"variable","tokens":[{"end":82,"kind":"keyword","start":0,"text":"let"}]}
        let typeck_root_def_id = tcx.typeck_root_def_id(self.mir_def.to_def_id());
        let tcx = self.infcx.tcx;
        let identity_args = GenericArgs::identity_for_item(tcx, typeck_root_def_id);