Datetime: a time without a zone leaves a question open

Useful to know

Python distinguishes datetime objects with time-zone information from those without it. A value such as 12:00 does not by itself identify the same instant for readers in different countries. [1]

Choose a consistent UTC and time-zone policy for interchange. Do not merely attach an arbitrary zone label to a local time when conversion is required. Describing a value and converting between zones are different operations.