public static function unique($arr)
	{
		// filter out all duplicate values
		return array_filter(
			$arr,
			function ($item)
			{
				// contrary to popular belief, this is not as static as you think...
				static $vars = array();

				if (in_array($item, $vars, true))
				{
					// duplicate
					return false;
				}
				else
				{
					// record we've had this value
					$vars[] = $item;

					// unique
					return true;
				}
			}
		);
	}