Trying to create a method to verify time

I'm new to python and i've been taking some courses to try and get the hang of it, as a proyect to challenge myself i tried to recreate a library method to check for borrowed books and etc. However i wanna do it manually without using python's functions

However i am kind of lost in how to create the method to verify that the time has the correct format (it's supposed to be dd/mm/2023)

I've been using this code i found as a guide

import datetime i def check_date(year, month, day): correctDate = None try: newDate = datetime.datetime(year, month, day) correctDate = True except ValueError: correctDate = False return correctDate

but i cannot find a way to make it work by myself