{"ast_node_type":"other","tokens":[{"end":33,"kind":"keyword","start":0,"text":"Some(def_id)"}]}
                Some(def_id) => {
            let guar = match region.opt_param_def_id(self.tcx, self.impl_m_def_id) {
                    let return_span = if let ty::Alias(ty::Opaque, opaque_ty) = self.ty.kind() {