Really, really simple extension or extension template

I am about to write my first Yii 2 extension. I read the manual:

And while it is professionally written it is by nature a bit dry in contents, especially for someone who never did an extension for Yii 2.

Does anyone can list some Yii 2 extension that are really, really simple in nature? Simple enough that forking it could be used as an example / based for my own extension? Or maybe there is some boilerplate / template to be used for such purpose? Thank you!