namespace quality_equiv {

int observable_state = 0;

int doubledByAddition(int value) { return value + value; }

int doubledByMultiplication(int value) { return value * 2; }

int writeOne(int value) {
    observable_state = 1;
    return value + 1;
}

int writeTwo(int value) {
    observable_state = 2;
    return value + 1;
}

} // namespace quality_equiv