App: differentiate shared callback

In the app, I want to share a callback between two buttons (app.Button1 and app.Button2). However, I want the action to be slightly different if Button1 is pushed vs Button2: something on the order of x=1 vs x=3.

Is there a way to detect, in the callback, which button triggered it?

(Matlab 2018a)

[Geoff Hayes]

Jessica - what does the signature for your callback look like? Isn't there a src input parameter?

[Jessica Hiscocks]

Not so far as I can tell- that seems to only apply if you create the button programmatically after the app is running.