Array
(
    [1880] => Array
        (
            [parent_category_id] => 1880
            [parent_category] => Array
                (
                    [id] => 1880
                    [slug] => engineering
                    [name] => Engineering
                )

            [subcategories] => Array
                (
                    [0] => Array
                        (
                            [name] => Mechanical Engineering
                            [slug] => mechanical-engineering
                            [id] => 1881
                        )

                )

        )

    [1723] => Array
        (
            [parent_category_id] => 1723
            [parent_category] => Array
                (
                    [id] => 1723
                    [slug] => math
                    [name] => Math
                )

            [subcategories] => Array
                (
                    [0] => Array
                        (
                            [name] => Algebra 1
                            [slug] => algebra-1
                            [id] => 1725
                        )

                    [1] => Array
                        (
                            [name] => Algebra 2
                            [slug] => algebra-2
                            [id] => 1726
                        )

                    [2] => Array
                        (
                            [name] => Calculus
                            [slug] => calculus
                            [id] => 1730
                        )

                    [3] => Array
                        (
                            [name] => Differential Equations
                            [slug] => differential-equations
                            [id] => 1731
                        )

                    [4] => Array
                        (
                            [name] => Discrete Math
                            [slug] => discrete-math
                            [id] => 1732
                        )

                    [5] => Array
                        (
                            [name] => Elementary Math
                            [slug] => elementary-math
                            [id] => 1743
                        )

                    [6] => Array
                        (
                            [name] => Geometry
                            [slug] => geometry
                            [id] => 1727
                        )

                    [7] => Array
                        (
                            [name] => Linear Algebra
                            [slug] => linear-algebra
                            [id] => 1733
                        )

                    [8] => Array
                        (
                            [name] => Prealgebra
                            [slug] => prealgebra
                            [id] => 1724
                        )

                    [9] => Array
                        (
                            [name] => Precalculus
                            [slug] => precalculus
                            [id] => 1728
                        )

                    [10] => Array
                        (
                            [name] => Trigonometry
                            [slug] => trigonometry
                            [id] => 1729
                        )

                )

        )

)