* 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) {

      Range<C> range = ranges.get(index);
      return range.contains(value) ? range : null;
    }
    return null;
  }

  @Override
  public Range<C> span() {
    if (ranges.isEmpty()) {
      throw new NoSuchElementException();
    }
    return Range.create(ranges.get(0).lowerBound, ranges.get(ranges.size() - 1).upperBound);
  }

  @Override
  public boolean isEmpty() {
    return ranges.isEmpty();

    }
  }

  @Override
  public Range<K> span() {
    if (ranges.isEmpty()) {
      throw new NoSuchElementException();
    }
    Range<K> firstRange = ranges.get(0);
    Range<K> lastRange = ranges.get(ranges.size() - 1);
    return Range.create(firstRange.lowerBound, lastRange.upperBound);
  }

  /**
   * Guaranteed to throw an exception and leave the {@code RangeMap} unmodified.
   *

      for (Range<Integer> range2 : RANGES) {
        for (Range<Integer> range3 : RANGES) {
          Map<Integer, Integer> model = new HashMap<>();
          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) {

        assertTrue(CharUtil.isUrlChar('9')); // last digit

        // Test characters just outside ranges that are not valid
        assertFalse(CharUtil.isUrlChar('`')); // backtick (just before 'a')
        assertFalse(CharUtil.isUrlChar('{')); // left brace (just after 'z')
        assertFalse(CharUtil.isUrlChar('^')); // caret (before 'a' range)
        assertFalse(CharUtil.isUrlChar('|')); // pipe (not in valid set)
    }

  }

  @Override
  public void put(Range<K> range, V value) {
    if (!range.isEmpty()) {
      checkNotNull(value);
      remove(range);
      entriesByLowerBound.put(range.lowerBound, new RangeMapEntry<K, V>(range, value));
    }
  }

  @Override
  public void putCoalescing(Range<K> range, V value) {
    // don't short-circuit if the range is empty - it may be between two ranges we can coalesce.

  }

  @Override
  public void put(Range<K> range, V value) {
    if (!range.isEmpty()) {
      checkNotNull(value);
      remove(range);
      entriesByLowerBound.put(range.lowerBound, new RangeMapEntry<K, V>(range, value));
    }
  }

  @Override
  public void putCoalescing(Range<K> range, V value) {
    // don't short-circuit if the range is empty - it may be between two ranges we can coalesce.

     * Gets the artifact coordinates whose version range should be resolved.
     * The coordinates may contain a version range (e.g., "[1.0,2.0)") or a single version.
     *
     * @return the artifact coordinates, never {@code null}
     */
    @Nonnull
    ArtifactCoordinates getArtifactCoordinates();

    /**
     * Gets the nature of repositories to query when resolving the version range.

        String result = XmlUtil.stripInvalidXMLCharacters(input);
        assertEquals("TestValidText", result);
    }

    public void test_stripInvalidXMLCharacters_validRanges() {
        // Test valid character ranges
        String input = "Test" + String.valueOf((char) 0x0020) // space
                + String.valueOf((char) 0x0009) // tab
                + String.valueOf((char) 0x000A) // line feed