* also be called their <i>union</i>. If they are not, note that the span might contain values
   * that are not contained in either input range.
   *
   * <p>Like {@link #intersection(Range) intersection}, this operation is commutative, associative
   * and idempotent. Unlike it, it is always well-defined for any two input ranges.
   */
  public Range<C> span(Range<C> other) {

      for (Range<Integer> range2 : RANGES) {
        for (Range<Integer> range3 : RANGES) {
          Map<Integer, Integer> model = Maps.newHashMap();
          putModel(model, range1, 1);
          putModel(model, range2, 2);
          putModel(model, range3, 3);
          RangeMap<Integer, Integer> test = TreeRangeMap.create();
          RangeMap<Integer, Integer> test2 = TreeRangeMap.create();

    List<Range<C>> asRanges = ImmutableList.copyOf(rangeSet.asRanges());

    // test that connected ranges are coalesced
    for (int i = 0; i + 1 < asRanges.size(); i++) {
      Range<C> range1 = asRanges.get(i);
      Range<C> range2 = asRanges.get(i + 1);
      assertFalse(range1.isConnected(range2));
    }

    // test that there are no empty ranges
    for (Range<C> range : asRanges) {

      for (Range<Integer> range2 : ranges) {
        if (!range1.isConnected(range2) || range1.intersection(range2).isEmpty()) {
          ImmutableRangeSet<Integer> rangeSet =
              ImmutableRangeSet.<Integer>builder().add(range1).add(range2).build();
          for (Range<Integer> subRange : subRanges) {
            RangeSet<Integer> expected = TreeRangeSet.create();
            for (Range<Integer> range : rangeSet.asRanges()) {

                ranges.add(new RangeValue(token.replace("]", ""), true));
            } else if (token.endsWith(")")) {
                ranges.add(new RangeValue(token.replace(")", ""), false));
            } else if (token.isEmpty()) {
                ranges.add(new RangeValue("", false));
            }
        }
        if (ranges.size() < 2) {
            ranges.add(new RangeValue("99999999", false));
        }

  /**
   * Returns the range containing this key and its associated value, if such a range is present in
   * the range map, or {@code null} otherwise.
   */
  @CheckForNull
  Entry<Range<K>, V> getEntry(K key);

  /**
   * Returns the minimal range {@linkplain Range#encloses(Range) enclosing} the ranges in this
   * {@code RangeMap}.
   *
   * @throws NoSuchElementException if this range map is empty
   */
  Range<K> span();

  /**

  @GwtIncompatible // java.math.BigInteger
  public void testMean() {
    // Odd-sized ranges have an obvious mean
    assertMean(2, 1, 3);

    assertMean(-2, -3, -1);
    assertMean(0, -1, 1);
    assertMean(1, -1, 3);
    assertMean((1L << 62) - 1, -1, Long.MAX_VALUE);

    // Even-sized ranges should prefer the lower mean
    assertMean(2, 1, 4);
    assertMean(-3, -4, -1);
    assertMean(0, -1, 2);

  /** The HTTP {@code User-Agent} header field name. */
  public static final String USER_AGENT = "User-Agent";

  // HTTP Response header fields

  /** The HTTP {@code Accept-Ranges} header field name. */
  public static final String ACCEPT_RANGES = "Accept-Ranges";
  /** The HTTP {@code Access-Control-Allow-Headers} header field name. */
  public static final String ACCESS_CONTROL_ALLOW_HEADERS = "Access-Control-Allow-Headers";

   * works better than Ordering.natural().nullsFirst() because, if null comes before all other
   * values, it lies outside the submap/submultiset ranges we test, and the variety of tests that
   * exercise null handling fail on those subcollections.
   */
  public abstract static class NullsBefore implements Comparator<@Nullable String>, Serializable {
    /*

    List<Range<C>> asRanges = ImmutableList.copyOf(rangeSet.asRanges());

    // test that connected ranges are coalesced
    for (int i = 0; i + 1 < asRanges.size(); i++) {
      Range<C> range1 = asRanges.get(i);
      Range<C> range2 = asRanges.get(i + 1);
      assertFalse(range1.isConnected(range2));
    }

    // test that there are no empty ranges
    for (Range<C> range : asRanges) {