public function getDepth()
    {
        return array_reduce(
            $this->cartLines->toArray(),
            function ($depth, CartLineInterface $cartLine) {
                return max($depth, $cartLine->getDepth());
            },
            0
        );
    }
public function getDepth()
    {
        return array_reduce(
            $this->cartLines->toArray(),
            function ($depth, CartLineInterface $cartLine) {
                return max($depth, $cartLine->getDepth());
            },
            0
        );
    }
public function getDepth ( ) { return array_reduce ( $ this -> cartLines -> toArray ( ) , function ( $ depth , CartLineInterface $ cartLine ) { return max ( $ depth , $ cartLine -> getDepth ( ) ) ; } , 0 ) ; }
Return the maximum depth of all the cartLines.

@return int Depth
Return the maximum depth of all the cartLines .