[issue37908] Add some examples of ArgumentParser.exit()

[hai shi]

hai shi <shihai1991 at 126.com> added the comment:

Adding an example of ArgumentParser.exit(), because some user would like cathing errors manually or consider exit progress or not when an error occurs.

I have not add example of ArgumentParser.error(), because i can not think some user scenarios:(

----------

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue37908>
_______________________________________