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

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

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

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

                    [3] => Array
                        (
                            [name] => Probability
                            [slug] => probability
                            [id] => 1735
                        )

                    [4] => Array
                        (
                            [name] => Statistics
                            [slug] => statistics
                            [id] => 1736
                        )

                )

        )

    [1744] => Array
        (
            [parent_category_id] => 1744
            [parent_category] => Array
                (
                    [id] => 1744
                    [slug] => science
                    [name] => Science
                )

            [subcategories] => Array
                (
                    [0] => Array
                        (
                            [name] => Astronomy
                            [slug] => astronomy
                            [id] => 1758
                        )

                    [1] => Array
                        (
                            [name] => Physical Science
                            [slug] => physical-science
                            [id] => 1745
                        )

                    [2] => Array
                        (
                            [name] => Physics
                            [slug] => physics
                            [id] => 1748
                        )

                )

        )

)