{"ast_node_type":"other","tokens":[{"end":33,"kind":"keyword","start":0,"text":"|(param_ty,"}]}
            |(param_ty, ident)| {
        let Some(this_name) = params.iter().zip(tcx.hir_body_param_idents(closure.body)).find_map(
                // FIXME: also support deref for stuff like `Rc` arguments