String functions "cannot find symbol"

Omit "static" in line "function......." !    (or take public, private or hidden)

Works for me!  

    System.println(splitString("Test-String", "-"));        


    function splitString(str as String, delim as String) as Array<String or Null> {
		var posSep = str.find(delim);
		if(posSep != null) {
			var strLeft = str.substring(0, posSep);
			return [strLeft, str.substring(posSep+1, str.length())];
		}

		return [str, ""];
	}

Returns:   [Test, String]

This seems to be a util class. With omitting "static" it works for Monkey C but there is a risk that a new class instance will be created during each method call. But who knows how does it really work under the hood...