wp_is_mobile() function not working in child theme wordpress

I have created child theme of motion picture parent theme. what I am trying to do is redirect the page if it is mobile.

if ( wp_is_mobile() ) {
    function mobile_home_redirect(){

        include( get_stylesheet_directory() . '/abc.php' );
        exit;

    }
    add_action( 'template_redirect', 'mobile_home_redirect' );

}

Any help would be greatly appreciated!