Raise exception vs. return None in functions?

Question

What\'s better practice in a user-defined function in Python: raise an exception or return None? For example, I have a function that finds the mos

Answer 1

with python 3.5's typing:

example function when returning None will be:

def latestpdf(folder: str) -> Union[str, None]

and when raising an exception will be:

def latestpdf(folder: str) -> str 

option 2 seem more readable and pythonic

(+option to add comment to exception as stated earlier.)