WP create categories and sub categories programmatically

function create_cat_settings() {
     wp_create_category( 'Videos' );
 $parent_term_a = term_exists( 'Videos', 'category' ); // array is returned if taxonomy is given
$parent_term_a_id = $parent_term_a['term_id']; // get numeric term id
 // First subcategory
wp_insert_term(
    'World', // the term 
    'category', // the taxonomy
    array(
        // 'description'=> 'Some description.',
        'slug' => 'world',
        'parent'=> $parent_term_a_id
    )
);
 // Second subcategory
wp_insert_term(
    'Movies', // the term 
    'category', // the taxonomy
    array(
        // 'description'=> 'Some description.',
        'slug' => 'movies',
        'parent'=> $parent_term_a_id
    )
);
 // Third subcategory
wp_insert_term(
    'Circket', // the term 
    'category', // the taxonomy
    array(
        // 'description'=> 'Some description.',
        'slug' => 'circket',
        'parent'=> $parent_term_a_id
    )
);
wp_insert_term(
    'Tech', // the term 
    'category', // the taxonomy
    array(
        // 'description'=> 'Some description.',
        'slug' => 'tech',
        'parent'=> $parent_term_a_id
    )
);	
wp_insert_term(
    'Auto', // the term 
    'category', // the taxonomy
    array(
        // 'description'=> 'Some description.',
        'slug' => 'auto',
        'parent'=> $parent_term_a_id
    )
);	
wp_insert_term(
    'Top News', // the term 
    'category', // the taxonomy
    array(
        // 'description'=> 'Some description.',
        'slug' => 'top-news',
        'parent'=> $parent_term_a_id
    )
);		
}
add_action( 'admin_init', 'create_cat_settings' );