public void rotate(int index, int len, int distance) {
    	checkRange(index, len);
    	doRotate(index, len, distance);
    }
Rotate specified elements in the list.
The distance argument can be positive or negative:
If it is positive, the elements are moved towards the end,
if negative, the elements are moved toward the beginning,
if distance is 0, the list is not changed.

@param index		index of first element to rotate
@param len		number of elements to rotate
@param distance	distance to move the elements
@throws 			IndexOutOfBoundsException if the ranges are invalid
jphp-runtime/src/php/runtime/memory/support/IList.java