2. The return value of time.time() is actually a floating-point number ... It's also not guaranteed to be monotonically increasing, which is a whole other thing that can trip people up, but that will have to be a separate blog post.

Oh god, I didn't realize that about Python and the POSIX spec. Cautiously, I'm going to guess that GPS seconds are one of the few reliable ways to uniformly convey a monotonically-increasing time reference.

Python has long since deprecated the datetime.datetime.utcnow() function, because it produces a naive object that is ostensibly in UTC.

Ok, this is just a plainly bad decision then and now by the datetime library people. What possible reason could have existed to produce a TZ-naive object from a library call that only returns a reference to UTC?