syntax_data: {"ast_node_type":"function","tokens":[{"end":56,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn new(tcx: TyCtxt<'tcx>, def: LocalDefId) -> Self {
context_before: impl<'tcx> ThirBuildCx<'tcx> {
context_after:         let typeck_results = tcx.typeck(def);