syntax_data: {"ast_node_type":"other","tokens":[{"end":49,"kind":"keyword","start":0,"text":"used_region_names:"}]}
source_snippet:             used_region_names: FxHashSet<Symbol>,
context_before:             tcx: TyCtxt<'tcx>,
context_after:             type_collector: SsoHashSet<Ty<'tcx>>,