* #transform} methods all return {@link Double#NaN}. The {@link #inverse} method returns the same
   * instance.
   */
  public static LinearTransformation forNaN() {
    return NaNLinearTransformation.INSTANCE;
  }

  /** Returns whether this is a vertical transformation. */
  public abstract boolean isVertical();

   *
   * <p>If the dataset contains any non-finite values ({@link Double#POSITIVE_INFINITY}, {@link
   * Double#NEGATIVE_INFINITY}, or {@link Double#NaN}) then the result is {@link
   * LinearTransformation#forNaN()}.
   *
   * @throws IllegalStateException if the dataset is empty or contains a single pair of values, or
   *     both the {@code x} and {@code y} dataset have zero population variance
   */

   *
   * <p>If the dataset contains any non-finite values ({@link Double#POSITIVE_INFINITY}, {@link
   * Double#NEGATIVE_INFINITY}, or {@link Double#NaN}) then the result is {@link
   * LinearTransformation#forNaN()}.
   *
   * @throws IllegalStateException if the dataset is empty or contains a single pair of values, or
   *     both the {@code x} and {@code y} dataset must have zero population variance
   */

    assertThat(transformation.inverse().inverse()).isSameInstanceAs(transformation);
  }

  /**
   * Asserts that {@code transformation} behaves as expected for {@link
   * LinearTransformation#forNaN}.
   */
  static void assertLinearTransformationNaN(LinearTransformation transformation) {
    assertThat(transformation.isHorizontal()).isFalse();
    assertThat(transformation.isVertical()).isFalse();

  /**
   * Converts the specified {@code String str} from this format to the specified {@code format}. A
   * "best effort" approach is taken; if {@code str} does not conform to the assumed format, then
   * the behavior of this method is undefined but we make a reasonable effort at converting anyway.
   */
  public final String to(CaseFormat format, String str) {
    checkNotNull(format);
    checkNotNull(str);

        final Date date = toDate("11:49");
        assertThat(new SimpleDateFormat("HH:mm:ss").format(date), is("11:49:00"));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testToDate_MediumStyle() throws Exception {
        final Date date = toDate("11:49:10");
        assertThat(new SimpleDateFormat("HH:mm:ss").format(date), is("11:49:10"));
    }

    /**
     * @throws Exception
     */

        assertThat(new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(date), is("2010/09/07 11:49:00"));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testToDate_MediumStyle() throws Exception {
        final Date date = toDate("2010/9/7 11:49:10", Locale.JAPAN);
        assertThat(new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(date), is("2010/09/07 11:49:10"));
    }

    /**

    assertThat(function.apply("Null")).isNull();

    new EqualsTester()
        .addEqualityGroup(function, Functions.forMap(map, 42))
        .addEqualityGroup(Functions.forMap(map))
        .addEqualityGroup(Functions.forMap(map, null))
        .addEqualityGroup(Functions.forMap(map, 43))
        .testEquals();
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester

  /**
   * Converts the specified {@code String str} from this format to the specified {@code format}. A
   * "best effort" approach is taken; if {@code str} does not conform to the assumed format, then
   * the behavior of this method is undefined but we make a reasonable effort at converting anyway.
   */
  public final String to(CaseFormat format, String str) {
    checkNotNull(format);
    checkNotNull(str);

    return result
  }
  synchronized(BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS) {
    for (i in 0 until BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS.size) {
      var format: DateFormat? = BROWSER_COMPATIBLE_DATE_FORMATS[i]
      if (format == null) {
        format =
          SimpleDateFormat(BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS[i], Locale.US).apply {