public static HashSet<Integer> createSet() {
        HashSet<Integer> set1 = new HashSet<>();
        for (int i = 0; i <20 ; i++) {
            set1.add(i);

        }
        return set1;
    }

    public static HashSet<Integer> removeAllNumbersMoreThan10(HashSet<Integer> set) {
        for (Integer a : set) {
            if (a > 10) {
                set.remove(a);
            }

        }
        return set;
    }