/**
  * Follow the parent chain an merge template and config variables
  *
  * @param \Smarty_Internal_Data|null $data
  */
 public function _mergeVars(Smarty_Internal_Data $data = null)
 {
     if (isset($data)) {
         if (!empty($this->tpl_vars)) {
             $data->tpl_vars = array_merge($this->tpl_vars, $data->tpl_vars);
         }
         if (!empty($this->config_vars)) {
             $data->config_vars = array_merge($this->config_vars, $data->config_vars);
         }
     } else {
         $data = $this;
     }
     if (isset($this->parent)) {
         $this->parent->_mergeVars($data);
     }
 }