src/Valkyrja/Container/NativeContainer.php
public function has(string $serviceId): bool
    {
        return isset(self::$services[$serviceId]) || isset(self::$aliases[$serviceId]);
    }
public function has(string $serviceId): bool
    {
        return isset(self::$services[$serviceId]) || isset(self::$aliases[$serviceId]);
    }
Check whether a given service exists.

@param string $serviceId The service

@return bool