duck

function FollowTrail() {
    for (var i=0; i < trail.Length-1; ++i)
    {
        p1 = trail[i];
        p2 = trail[i+1];
        dist = (p1-p2).magnitude;
        lerpDist = 0.0;

        while (lerpDist < dist) {
            i = lerpDist / dist;
            pos = Vector3.Lerp(p1, p2, i);
            yield;
            lerpDist += Time.deltaTime * speed;
        }
    }
}