https://docs.python.org/3.7/library/time.html contains the text "UTC is Coordinated Universal Time (formerly known as Greenwich Mean Time, or GMT)". This is not strictly true. Referring to https://en.wikipedia.org/wiki/Coordinated_Universal_Time the definition of UTC is in terms of frequency standards, GMT in terms of astronomy. Hence with GMT each minute has exactly 60 seconds, but the length of the second may vary slightly to account for changes in the Earth's rotation. With UTC each second is the same length, but "leap seconds" can be inserted or removed giving 59 and 61 second minutes. The leap seconds keep the two systems in sync to less than one second.

This of course only matters for the most critical applications, but it would be worth documenting correctly.