function format_varname($str) {
$str = preg_replace("/([a-z])([A-Z])/", "\\1_\\2", $str); # split words on camelCase
$str = strtolower($str);
+ $str = preg_replace("/['‘’]/", '', $str);
$str = preg_replace('/[^a-z0-9_]+/', '_', $str);
return preg_replace('/^([^a-z_])/', "_\\1", $str);
}