F(0) = 0
F(1) = 1
F(n) = F(n-1) + F(n-2)

   @Test
    public void clac() {
        int value = clacFibonacci(6);
        System.out.println("value: " + value);
    }

    public int clacFibonacci(int n) {
        if (n == 0) {
            return 0;
        }
        if (n == 1) {
            return 1;
        }

        return clacFibonacci(n - 1) + clacFibonacci(n - 2);
    }