{"ast_node_type":"other","tokens":[{"end":61,"kind":"keyword","start":0,"text":"opaque_type_span:"}]}
            opaque_type_span: self.tcx.def_span(self.def_id),
                .unwrap_or_else(|| self.tcx.def_span(item_def_id)),
            opaque_type: self.tcx.def_path_str(self.def_id),