syntax_data: {"ast_node_type":"function","tokens":[{"end":68,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn upcast_from(from: Clause<'tcx>, _tcx: TyCtxt<'tcx>) -> Self {
context_before: impl<'tcx> UpcastFrom<TyCtxt<'tcx>, Clause<'tcx>> for Predicate<'tcx> {
context_after:         from.as_predicate()