Don't know how to use yapf

Hi,
I have enabled the yapf, but I don't know when or how to use it. Before I use the atom beautifier package with yapf and I need to use ctl+opt+b to format my code. So how to use it?

The issue mentions YAPF, Atom Beautifier, and the Ctrl+Opt+B shortcut, but names no file, test, or entry point. First inspect the repository's formatter integration and existing usage documentation; done means documenting the supported way to invoke formatting and the expected shortcut or limitation.

Written by the indexing model from the issue text.