Cutom output format

Hi!
I am trying to create a script that can save an animation from aseprite to my own custom file format. I already have the python script that converts a aseprite file to my format and i am able to run that script from Lua. The only problem that i have is that i first need to save the animation as a aseprite file and then converting it and if that is going to work, then i need to be able to get the path to were the file was saved. Are there any way to use app.command.SaveFileAs and get the path it saved the file to? If not, can i send an argument to app.command.SaveFileAs which says where it should save it?