syntax_data: {"ast_node_type":"other","tokens":[{"end":73,"kind":"keyword","start":0,"text":"impl<'tcx>"}]}
source_snippet: impl<'tcx> UpcastFrom<TyCtxt<'tcx>, TraitRef<'tcx>> for Predicate<'tcx> {
context_after:     fn upcast_from(from: TraitRef<'tcx>, tcx: TyCtxt<'tcx>) -> Self {