Why do we put comma after number in "print("%02d" % (number,))"?

Hi, I was reading stackoverflow: python - Display number with leading zeros - Stack Overflow
which was about displaying a leading zero for all numbers. Ex) 1 → 01, 001, etc.
The code answer was

number = 1
print("%02d" % (number,))

which of course worked, but I was wondering why there is a comma after the number. Do you think this was just a typo?
How is it possible that we didn’t get any error when there was an additional comma after an argument?
Thank you in advance

I think (number,) makes a tuple with number in it, whereas (number) would not do so.