{"ast_node_type":"function","tokens":[{"end":67,"kind":"keyword","start":0,"text":"fn"}]}
fn prepare_usage_sets<'tcx>(tcx: TyCtxt<'tcx>) -> UsageSets<'tcx> {
/// is an "unused function" for coverage purposes.
    let MonoItemPartitions { all_mono_items, codegen_units, .. } =