function rate(sound_name, ...args) {
	const sound = audioTracks[sound_name];
	if (sound && typeof sound !== "undefined") {
		return sound.rate(...args);
	} else {
		throw new Error("audio clip " + sound_name + " does not exist");
	}
}
get or set the rate of playback for a sound.
@param {string} sound_name - audio clip name - case sensitive
@param {number} [rate] - playback rate : 0.5 to 4.0, with 1.0 being normal speed.
@param {number} [id] - the sound instance ID. If none is passed, all sounds in group will be changed.
@returns {number} return the current playback rate (if no extra parameters were given)
@example
// get the playback rate of the background music
let rate = me.audio.rate("dst-gameforest");
// speed up the playback of the background music
me.audio.rate("dst-gameforest", 2.0);