}
		})
	}
}

func TestToStringKey(t *testing.T) {
	cases := []struct {
		values []interface{}
		key    string
	}{
		{[]interface{}{"a"}, "a"},
		{[]interface{}{1, 2, 3}, "1_2_3"},
		{[]interface{}{1, nil, 3}, "1_nil_3"},
		{[]interface{}{[]interface{}{1, 2, 3}}, "[1 2 3]"},
		{[]interface{}{[]interface{}{"1", "2", "3"}}, "[1 2 3]"},
		{[]interface{}{[]interface{}{"1", nil, "3"}}, "[1 <nil> 3]"},
	}

                "6_1_1",
                "6_1_2",
                "6_1_3",
                "6_1_4",
                "6_2_0",
                "6_2_1",
                "6_2_2",
                "6_2_3",
                "6_2_4",
                "6_3_0",
                "6_3_1",
                "6_3_2",
                "6_4_0",
                "6_4_1",
                "6_4_2",
                "6_5_0",