Add custom stats in download stats section of Quiz

customiser_class.php

<?php

if(!class_exists('WPLMS_Customizer_Plugin_Class'))
{   
    class WPLMS_Customizer_Plugin_Class  // We'll use this just to avoid function name conflicts 
    {
        public function __construct(){   
          add_filter('wplms_download_mod_stats_fields',array($this,'custom_wplms_download_mod_stats_fields'),10,2);
          add_action('wplms_mod_stats_process',array($this,'custom_wplms_mod_stats_process'),10,7);
        } // END public function __construct
        
        public function activate(){
            // ADD Custom Code which you want to run when the plugin is activated
        }
        public function deactivate(){
            // ADD Custom Code which you want to run when the plugin is de-activated    
        } 

        function custom_wplms_download_mod_stats_fields($fields,$type){
            if($type == 'quiz'){
                $fields['user_email'] = 'User Email';
            }
            return $fields;
        }

        function custom_wplms_mod_stats_process(&$csv_title, &$csv,&$i,&$id,&$user_id,&$field,&$post_type){
            if($post_type != 'quiz')
                return;
            if($field != 'user_email') // Ensures the field was checked.
             return;

            $title=__('Student Email','vibe');
            if(!in_array($title,$csv_title))
              $csv_title[$i]=$title;
      
            $user = get_userdata( $user_id );
            $csv[$i][]= $user->user_email;
        }
        // ADD custom Code in clas
        
    } // END class WPLMS_Customizer_Class
} // END if(!class_exists('WPLMS_Customizer_Class'))

?>