Ignoring coding standards

WordPress uses global variables to maintain certain data structures. As per the coding standards, you should not change the values of global variables.

public function highlight_draft_submenu( $parent_file ) { 
    global $submenu_file; 
    // Only update the submenu file value if we're on the Scheduled page. 
    if ( 'draft' === get_query_var( 'post_status' ) ) {
        /** * Removing unnecessary code for the purposes of the demo. Assume * there is an associative array of key/value pairs referened by * a variabled named `$args`. */
        // @codingStandardsIgnoreStart

        $submenu_file = add_query_arg( $args, $url );
        // @codingStandardsIgnoreEnd 
    return $parent_file;