/**
 * Sets the string used to indent HTML
 *
 * @param   string  $string  String used to indent ("\11", "\t", '  ', etc.).
 *
 * @return  Document instance of $this to allow chaining
 *
 * @since   1.7.0
 */
public function setTab($string)
{
    $this->_tab = $string;
    return $this;
}