public function markup($markup = null, $callback1 = null, $callback2 = null, $callback3 = null)
{
$args = func_get_args();
if ($this->documentWrapper->isXML) {
return call_user_func_array(array($this, 'xml'), $args);
} else {
return call_user_func_array(array($this, 'html'), $args);
}
}