code: static boolean isGreaterThanOrEqualToDuration(Unit unit,
              long position1, long position2, int duration) {
          return unit.addToPosition(position1, duration + 1) - 1 >= position2;
      }
docs: Determines whether <code>position1</code> plus <code>distance</code> is
  greater than or equal to <code>position2</code>.
  
  @param position1
  a <code>long</code>.
  @param position2
  a <code>long</code>.
  @param distance
  a <code>long</code>.
  @return <code>true</code> if <code>position1</code> plus
  <code>distance</code> is greater than or equal to
  <code>position2</code>, <code>false</code> if not.