private final ImmutableList<Range<C>> ranges;
    private final DiscreteDomain<C> domain;

    AsSetSerializedForm(ImmutableList<Range<C>> ranges, DiscreteDomain<C> domain) {
      this.ranges = ranges;
      this.domain = domain;
    }

    Object readResolve() {
      return new ImmutableRangeSet<C>(ranges).asSet(domain);
    }
  }

  /**

   * iterators that don't support remove, passing one to the FilteredEntryMultimap constructor would
   * lead to a multimap whose removal operations would fail. This method combines the predicates to
   * avoid that problem.
   */
  private static <K extends @Nullable Object, V extends @Nullable Object>
      Multimap<K, V> filterFiltered(

         */
        I result = requireNonNull(elements[index]);
        elements[index] = null;
        index++;
        return result;
      }
    };
  }

  /**
   * Combines two iterators into a single iterator. The returned iterator iterates across the
   * elements in {@code a}, followed by the elements in {@code b}. The source iterators are not
   * polled until necessary.
   *