public function scopeSort($query)
    {
        if (!$this->sorters) {

            $message = 'Please set the $sorters property.';
            throw new FilterableSortableException($message);
        }

        $this->sorters = app()->make($this->sorters);

        if (!$this->sorters instanceof QuerySorters) {

            $message = '$sorters property must be a class instance of QuerySorter.';
            throw new FilterableSortableException($message);
        }

        return $this->sorters->apply($query);
    }