Consider the following function: // Postcondition: The digits of the number have been written, // stacked vertically. If number is negative, then a negative // sign appears on top. void super_write_vertical(int number) { if (number < 0) { std::cout << '-' << endl; super_write_vertical(abs(number)); } else if (number < 10) { std::cout << number << endl; } else { super_write_vertical(number/10); std::cout << number % 10 << endl; } } What values of number are directly handled by the stopping case