Music for the battle arena, how to add new tracks.

I couldn't find any information on how to seamlessly add music to battles without replacing the existing tracks. I experimented with the files and their references to each other, and it seems to have worked. I can't say anything about bugs or other issues, but at first glance, and after the first and second tests, everything seems to be working smoothly. So, here's what I've learned about adding custom music to battles.
https://www.youtube.com/watch?v=Nv-We5wm97M



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