|null) $probe SuperCacheProbe::run(). * @return Closure(bool): list */ public static function extra(Closure $probe): Closure { return ProbeStep::extra(self::PROBE, self::LABEL, self::LABEL_CACHE_OFF, $probe); } public static function label(CheckStep $step): string { // Reports saved before labels were stored have none. return $step->label ?? ($step->key === self::PROBE ? self::LABEL : null) ?? CheckStep::genericLabel($step->key, SuperCacheCompatibility::LABEL) ?? $step->key; } }