{"ast_node_type":"other","tokens":[{"end":61,"kind":"keyword","start":0,"text":"///"}]}
    /// returns that function's `DefId` and `GenericArgsRef`.
    /// If a type is a reference or raw pointer to the anonymous type of a function definition,
    fn is_fn_ref(ty: Ty<'tcx>) -> Option<(DefId, GenericArgsRef<'tcx>)> {