Function pick_from_pool 

pub fn pick_from_pool<'a>(
    manifest: &'a AudioManifest,
    pool: &str,
    seed: u64,
) -> Option<&'a str>

The music cue pool pool yields for seed: the same seed always gives the same cue. None if the manifest has no such pool or it is empty. This is not a game’s simulation RNG, so a pick never changes a battle or its replay.