/**
* Convenience method for err() that wraps message between <warning /> tag
* @param string|array|null $message A string or an array of strings to
* output
* @param int $newlines Number of newlines to append
* @return int|bool Returns the number of bytes returned from writing to
* stdout
*/
public function warning($message = null, $newlines = 1)
{
return parent::warn($message, $newlines);
}