public function index($properties)
    {
        $properties = (array) $properties;

        foreach ($properties as $property)
        {
            $this->addCommand('index', ['property' => $property]);
        }
    }
public function index($properties)
    {
        $properties = (array) $properties;

        foreach ($properties as $property)
        {
            $this->addCommand('index', ['property' => $property]);
        }
    }
public function index ( $ properties ) { $ properties = ( array ) $ properties ; foreach ( $ properties as $ property ) { $ this -> addCommand ( 'index' , [ 'property' => $ property ] ) ; } }
Specify an index for the label properties.

@param  string|array  $properties
@return \Illuminate\Support\Fluent
Specify an index for the label properties .