App.run() documentation

Is there any documentation on the App.run() function I see in every python file example of the Arduino App lab?

All I have seen so far is this:

App.run(): Starts the Router Bridge runtime that enables the Python®-Arduino communication.

But I have also seen this:
App.run(user_loop=loop)

Just curious to understand some more details.

Thanks for any thoughts.

Updated:

I did find this in the bottom left of App Lab:

It has a little more info on App.run() under the “Waht is an App?” icon

You can find the code here app-bricks-py/src/arduino/app_utils/app.py at 14d2de61aaf36227e9cd5d58754922809dbd7ebf · arduino/app-bricks-py · GitHub