Flash Actionscript Tweening

function tween(mc, what, easeType, begin, end, time, then, onWhat) {
if (easeType == 1) {
myEase = Regular.easeInOut;
} else if (easeType == 2) {
myEase = Strong.easeInOut;
} else if (easeType == 3) {
myEase = Regular.easeOut;
} else if (easeType == 4) {
myEase = Strong.easeOut;
} else if (easeType == 5) {
myEase = Regular.easeIn;
} else if (easeType == 6) {
myEase = Strong.easeIn;
} else if (easeType == 7) {
myEase = None.easeNone;
} else if (easeType == 8) {
myEase = Back.easeOut;
}

var myTween:Tween = new Tween(mc, what, myEase, begin, end, time, false);
myTween.onMotionFinished = function() {
if (then != null) {
then.call();
}
//this.yoyo();
};

};