{"ast_node_type":"other","tokens":[{"end":9,"kind":"keyword","start":0,"text":"where"}]}
    where
    fn extract_existential_trait_ref<R, F>(&mut self, self_ty: Ty<'tcx>, mut closure: F) -> R
        F: FnMut(&mut ConfirmContext<'a, 'tcx>, Ty<'tcx>, ty::PolyExistentialTraitRef<'tcx>) -> R,