*
   * <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();

        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

 * <td>{@link DateFormat#SHORT} format</td>
 * <td>{@literal H:mm}</td>
 * </tr>
 * <tr>
 * <td>{@link DateFormat#MEDIUM} format</td>
 * <td>{@literal H:mm:ss}</td>
 * </tr>
 * <tr>
 * <td>{@link DateFormat#LONG} format</td>
 * <td>{@literal H:mm:ss z}</td>
 * </tr>
 * <tr>
 * <td>{@link DateFormat#FULL} format</td>
 * <td>{@literal H'時'mm'分'ss'秒' z}</td>
 * </tr>
 * <tr>

    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

     * @param format the date format pattern or "pdf_date" for PDF date format
     * @return parsed Date object, or null if parsing fails
     */
    public static Date parseDate(final String value, final String format) {
        if (value == null) {
            return null;
        }

        try {
            if (PDF_DATE.equals(format)) {
                final Calendar cal = DateConverter.toCalendar(value);

 * <td>{@link DateFormat#SHORT} format</td>
 * <td>{@literal yy/MM/dd}</td>
 * </tr>
 * <tr>
 * <td>{@link DateFormat#MEDIUM} format</td>
 * <td>{@literal yyyy/MM/dd}</td>
 * </tr>
 * <tr>
 * <td>{@link DateFormat#LONG} format</td>
 * <td>{@literal yyyy/MM/dd}</td>
 * </tr>
 * <tr>
 * <td>{@link DateFormat#FULL} format</td>
 * <td>{@literal yyyy'nen'M'gatsu'd'nichi'}</td>
 * </tr>

 * <td>{@link DateFormat#SHORT} format</td>
 * <td>{@literal yy/MM/dd H:mm}</td>
 * </tr>
 * <tr>
 * <td>{@link DateFormat#MEDIUM} format</td>
 * <td>{@literal yyyy/MM/dd H:mm:ss}</td>
 * </tr>
 * <tr>
 * <td>{@link DateFormat#LONG} format</td>
 * <td>{@literal yyyy/MM/dd H:mm:ss z}</td>
 * </tr>
 * <tr>
 * <td>{@link DateFormat#FULL} format</td>
 * <td>{@literal yyyy'年'M'月'd'日' H'時'mm'分'ss'秒' z}</td>