Custom Functions PHP in GP

<?php
/**
 * Generate child theme functions and definitions
 *
 * @package Generate
 */
 function generate_secondary_navigation_shortcode() {
      return generate_secondary_navigation_position();
}
add_shortcode( 'generate_secondary_navigation', 'generate_secondary_navigation_shortcode' );
?>
<!-- Strips More tag when Excerpt is used on post -->
<?php
add_filter('generate_more_tag','generate_disable_more_tag');
function generate_disable_more_tag()
{
      return false;
}
?>
<!-- End More tag -->
<!-- Add Previous Next buttons to bottom of Pages -->
<?php add_action( 'generate_after_content','generate_add_page_next_prev' );
function generate_add_page_next_prev()
{

      if ( ! is_page() )
            return;
?>
<div class="prev-next">
<?php
previous_post_link( '<div class="nav-previous prev-next-button"><span class="prev" title="' . __('Previous','generate') . '">%link</span></div>', 'Previous' );

next_post_link( '<div class="nav-next prev-next-button"><span class="next" title="' . __('Next','generate') . '">%link</span></div>', 'Next' );
?>
</div>
<?php
} ?>
<!-- End Previous Next buttons -->
<!-- Add PopMake script to footer -->
<?php
add_action( 'wp_footer', 'my_custom_popup_scripts', 500 );
function my_custom_popup_scripts() { ?>
    <script type="text/javascript">
    (function ($) {
        // Your custom code goes here.
        jQuery('#popmake-266')
    .on('popmakeBeforeOpen', function () {
        var $iframe = jQuery('iframe', jQuery(this)),
            src = $iframe.prop('src');
        $iframe.prop('src', '').prop('src', src + '?autoplay=1');
    });
        // Custom Code End.
    }(jQuery))
    </script><?php
}