Webmozart\Assert\Assert::subclassOf PHP Method

    public static function subclassOf($value, $class, $message = '')
    {
        if (!is_subclass_of($value, $class)) {
            static::reportInvalidArgument(sprintf($message ?: 'Expected a sub-class of %2$s. Got: %s', static::valueToString($value), static::valueToString($class)));
        }
    }

 /**
  * ContaoRepository constructor.
  *
  * @param string $modelClass Model class.
  */
 public function __construct($modelClass)
 {
     Assert::classExists($modelClass);
     Assert::subclassOf($modelClass, 'Model');
     $this->modelClass = $modelClass;
 }