}

  @Override
  public SampleElements<String> sampleKeys() {
    return new SampleElements<>("one", "two", "three", "four", "five");
  }

  @Override
  public SampleElements<String> sampleValues() {
    return new SampleElements<>("January", "February", "March", "April", "May");
  }

  @Override
  public Collection<String> createCollection(Iterable<? extends String> values) {
    return copyToSet(values);

    }

    @Override
    public SampleElements<String> sampleKeys() {
      return new SampleElements<>("one", "two", "three", "four", "five");
    }

    @Override
    public SampleElements<String> sampleValues() {
      return new SampleElements<>("january", "february", "march", "april", "may");
    }

    @Override
    public Collection<String> createCollection(Iterable<? extends String> values) {

    }

    @Override
    public SampleElements<String> sampleKeys() {
      return new SampleElements<>("one", "two", "three", "four", "five");
    }

    @Override
    public SampleElements<String> sampleValues() {
      return new SampleElements<>("january", "february", "march", "april", "may");
    }

    @Override
    public Collection<String> createCollection(Iterable<? extends String> values) {

   *     may or may not have {@code sampleKey} as a key.
   * @param sampleValue a key of the same type as that contained by {@code multimap}. {@code
   *     multimap} may or may not have {@code sampleValue} as a key.
   */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      void assertMultimapIsUnmodifiable(Multimap<K, V> multimap, K sampleKey, V sampleValue) {

   *     may or may not have {@code sampleKey} as a key.
   * @param sampleValue a key of the same type as that contained by {@code multimap}. {@code
   *     multimap} may or may not have {@code sampleValue} as a key.
   */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      void assertMultimapIsUnmodifiable(Multimap<K, V> multimap, K sampleKey, V sampleValue) {