code: private static Iterator<MarkerRange.Builder> addProjected(
        Predicate projected, String name,
        Iterator<MarkerRange.Builder> inner) {
      if (projected instanceof In) {
        return new SetIterator((In) projected, name, inner);
      } else if (projected instanceof Range) {
        return new RangeIterator(name, (Range) projected, inner);
      } else {
        return inner;
      }
    }
docs: Convenience function to add the correct {@link StackedIterator} to the key
  range Iterator stack.
  
  This method is used to add a <em>single</em> <em>projected</em> constraint
  to the stack.