WC_Emails::instance PHP Method

    public static function instance()
    {
        if (is_null(self::$_instance)) {
            self::$_instance = new self();
        }
        return self::$_instance;
    }

 /**
  * Render the settings for the current section
  *
  * @since 2.0.0
  */
 public function output()
 {
     $settings = $this->get_settings();
     // inject the actual setting value before outputting the fields
     // ::output_fields() uses get_option() but customizations are stored
     // in a single option so this dynamically returns the correct value
     if (isset($_GET['section']) && $_GET['section'] == 'email_options') {
         // email options
         $wc_emails = (array) WC_Emails::instance()->emails;
         foreach (self::$wc_emails_enabled as $filed => $id) {
             $email_enabled = (array) $wc_emails[$filed];
             if ($email_enabled['enabled'] == 'no') {
                 add_filter("pre_option_{$filed}", function () {
                     return 'no';
                 });
             } else {
                 add_filter("pre_option_{$filed}", function () {
                     return 'yes';
                 });
             }
         }
     }
     if (isset($_GET['section']) && $_GET['section'] == 'sms_options') {
     }
     foreach ($this->customizations as $filter => $value) {
         add_filter("pre_option_{$filter}", array($this, 'get_customization'));
     }
     WC_Admin_Settings::output_fields($settings);
 }