One of the things you learn when programming a lot is how to search for an answer based on knowledge already up for grabs!

Instead of answering you, I'll give you a hint: some coins have their open source code on GitHub. Think of a currency you use, or a popular one that you don't, and see if you can find their code to look through.

If you're having trouble while searching, I think the last one I looked at was Curecoin's wallet app. Curecoin.io should have you covered there if you want to check.