{"ast_node_type":"other","tokens":[{"end":5,"kind":"keyword","start":0,"text":"{"}]}
    {
    ) -> Option<(IndexVec<ExpectedIdx, (Option<GenericIdx>, FnParam<'_>)>, &hir::Generics<'_>)>
        let (sig, generics, body_id, params) = match self.tcx.hir_get_if_local(def_id)? {