public static function array_change_key_case($a, $mode)
	{
		if (! ReflectionTypeHint::isValid()) return false;
		if (! is_array($a)) return $a;
		$a2 = array();
		foreach ($a as $k => $v)
		{
			if (is_string($k))
			{
				$k = self::convert_case($k, $mode);
				if ($k === false) return false;
			}
			$a2[$k] = $v;
		}
		return $a2;
	}