function fade(sound_name, from, to, duration, id) {
	const sound = audioTracks[sound_name];
	if (sound && typeof sound !== "undefined") {
		sound.fade(from, to, duration, id);
	} else {
		throw new Error("audio clip " + sound_name + " does not exist");
	}
}
Fade a currently playing sound between two volumee.
@param {string} sound_name - audio clip name - case sensitive
@param {number} from - Volume to fade from (0.0 to 1.0).
@param {number} to - Volume to fade to (0.0 to 1.0).
@param {number} duration - Time in milliseconds to fade.
@param {number} [id] - the sound instance ID. If none is passed, all sounds in group will fade.