syntax_data: {"ast_node_type":"other","tokens":[{"end":31,"kind":"keyword","start":0,"text":")"}]}
source_snippet:     ) -> (Ty<'tcx>, Ty<'tcx>) {
context_before:         normalize: impl Fn(Ty<'tcx>) -> Ty<'tcx>,
context_after:         let (mut a, mut b) = (source, target);