code: public void setDuration(float start, float end)
      {
          for (GVRAnimation anim : mAnimations)
          {
              anim.setDuration(start,end);
          }
      }
docs: Sets the duration for the animations in this animator.
  
  @param start the animation will start playing from the specified time
  @param end the animation will stop playing at the specified time
  
  @see GVRAnimation#setDuration(float, float)