Does using modules in my Python code look more professional?

I'm fairly new to programming but I've managed to program little app in Python. I'd like to apply for entry level dev job and of course I want to show my code.

However it needs some serious refactoring and since I can't code everyday for many hours (my current day job) I want to be most efficient.

When I started coding the app I lacked some knowledge. The app has CLI. I wrote custom parser for that and later found out that there are modules out there that can handle it (argparse).

Now my question is: Does it look better if I use existing module than my own custom solution?

The advantage to custom solution is that it's already written, it works well and I also made tests for it. The downside is, I'm not 100% if my custom solution is quality code.