String (PyExpression[] args, int endElement) { String result = null; for (int i = 0; i < endElement; i++) { Object arg = evaluate(args[i]); if (!(arg instanceof String)) { return null; } if (result == null) { result = (String)arg; } else { result = FileUtil.toSystemIndependentName(Paths.get(result, (String)arg).toFile().getPath()); } } return result; }