code: public void removeUpdateListener(AnimatorUpdateListener listener) {
          if (mUpdateListeners == null) {
              return;
          }
          mUpdateListeners.remove(listener);
          if (mUpdateListeners.size() == 0) {
              mUpdateListeners = null;
          }
      }
docs: Removes a listener from the set listening to frame updates for this animation.
  
  @param listener the listener to be removed from the current set of update listeners
  for this animation.