How to make object turn around and go back to original place?

Alright guys, so I have made it so that my model goes from point A to point B and back, but I was wondering if it was possible to make it turn around instead of going in reverse back to its original spot? I know I should add some quaternion thing in there but not sure where or what...

Here's what I have so far:

 var pointB : Vector3;
 var speed = 20.0;
 var rotateSpeed = 3.0;
 
 function Start () {
     var pointA = transform.position;
    while (true) {
         yield MoveObject(transform, pointA, pointB, 20.0);
         yield MoveObject(transform, pointB, pointA, 20.0);
     }
 }
  
 function MoveObject (thisTransform : Transform, startPos : Vector3, endPos : Vector3, time : float) {
     var i = 0.0;
     var rate = 100.0/time;
     while (i < 1.0) {
        i += Time.deltaTime * rate;
         thisTransform.position = Vector3.Lerp(startPos, endPos, i);
         yield; 
     }
 }

Thanks!!