Inheritance: extends Mage2\Framework\System\Models\BaseModel
 private function _getProductBySlug($slug)
 {
     $slugAttribute = ProductAttribute::where('identifier', '=', 'slug')->get()->first();
     $productVarcharValue = ProductVarcharValue::where('product_attribute_id', '=', $slugAttribute->id)->where('value', '=', $slug)->where('website_id', '=', $this->websiteId)->get()->first();
     $product = Product::findorfail($productVarcharValue->product_id);
     return $product;
 }