Bind sorting order via parameter

[Flynnxx1]

Hello there,
I just started to explore vega lite, and really enjoyed it.

I was wandering if it's possible to bind sort to the parameter, that provides options for the end user to choose.
I found the following code online, it works but I do noticed there are some warming on the signal part.

Is there an example of documents that I can look into? And how to make it work , thank you for your help

https://stackoverflow.com/questions/67379937/change-mark-order-via-parameter