Sometimes you will have separated dates and times. This is particularly frequent when they are entered by a user. From an interaction point of view, it's usually easier to pick a date and then pick a time than to pick a date and a time together. Or you might be combining inputs from two different sources.
In all those cases, you will end up with a date and a time that you want to combine in a single datetime.datetime
instance.
The Python standard library provides support for such operations out of the box, so having any two of those:
>>> t = datetime.time(13, 30)
>>> d = datetime.date(2018, 1, 11)
We can easily combine them into a single entity:
>>> datetime.datetime.combine(d, t)
datetime.datetime(2018, 1, 11, 13, 30)