nit: I would probably create `var SYSTEM_VOLUME_MAX = 15;` that way if it ever changes in the future we avoid errors (updating value just in a single place and forgetting to update elsewhere). But since we only have 2 occurrences (with clear comments & very close to each other) I don't think we need to change it. - we could also remove comments from methods (since variable name already describes it), or keep it only on the variable declaration.