public static void main(String[] args) throws IOException {
        String[] tokens = readTokens();
        System.out.println("Tokens: " + Arrays.toString(tokens));
        System.out.println("Combinations:");
        for (int i = 0; i < tokens.length; i++) {
            for (int j = i; j < tokens.length; j++) {
                String combination = "{" + tokens[i] + " , " + tokens[j] + "}";
                System.out.println("  " + combination);
            }
        }
    }