So I have a program in Python for use on a Linux machine ... If my data has a zero byte, this is taken as the "end-of-string" terminator ('\0') by os.write() and nothing is written past that.

For some time now, Python has had the ability to “annotate” names with type information, in one form or another. With Python 3.5, type hints officially became part of the language (PEP 484).