{"ast_node_type":"other","tokens":[{"end":63,"kind":"keyword","start":0,"text":".param_def_id_to_index(tcx,"}]}
                .param_def_id_to_index(tcx, def_id.to_def_id())
            tcx.generics_of(item_def_id)
                .expect("expected generic param to be owned by item"),