/**
  * Remove a temporary overriding error callback
  * @see staticPushCallback()
  * @return array|string|false
  */
 public static function staticPopCallback()
 {
     $ret = array_pop(self::$overridecallback);
     if (!is_array(self::$overridecallback)) {
         self::$overridecallback = array();
     }
     return $ret;
 }