public function getCategoryTree($categoryId = null)
    {
        $method = 'category_tree';

        if ($categoryId !== null) {
            $method .= '/'.$categoryId;
        }

        return $this->call($method);
    }
public function getCategoryTree($categoryId = null)
    {
        $method = 'category_tree';

        if ($categoryId !== null) {
            $method .= '/'.$categoryId;
        }

        return $this->call($method);
    }
public function getCategoryTree ( $ categoryId = null ) { $ method = 'category_tree' ; if ( $ categoryId !== null ) { $ method .= '/' . $ categoryId ; } return $ this -> call ( $ method ) ; }
Get Category Tree

@docs https://docs.shopelloapi.com/#category-tree
Get Category Tree