/**
* underscore
* @desc turns a camelcased string to a lowercase underscored string
* @param string $word
* @access public
* @return string
*/
public static function underscore($word = null)
{
$tmp = Google_Base::replace($word, array('/([A-Z]+)([A-Z][a-z])/' => '\\1_\\2', '/([a-z\\d])([A-Z])/' => '\\1_\\2'));
return strtolower($tmp);
}