*
 * {@snippet :
 * public static double sqrt(double value) {
 *   if (value < 0) {
 *     throw new IllegalArgumentException("input is negative: " + value);
 *   }
 *   // calculate square root
 * }
 * }
 *
 * <p>to be replaced with the more compact
 *
 * {@snippet :
 * public static double sqrt(double value) {
 *   checkArgument(value >= 0, "input is negative: %s", value);

 *
 * {@snippet :
 * public static double sqrt(double value) {
 *   if (value < 0) {
 *     throw new IllegalArgumentException("input is negative: " + value);
 *   }
 *   // calculate square root
 * }
 * }
 *
 * <p>to be replaced with the more compact
 *
 * {@snippet :
 * public static double sqrt(double value) {
 *   checkArgument(value >= 0, "input is negative: %s", value);

   *
   * {@snippet :
   * ListMultimap<String, Integer> multimap = ImmutableListMultimap.of("a", 4, "a", 16, "b", 9);
   * Function<Integer, Double> sqrt = (Integer in) -> Math.sqrt((int) in);
   * ListMultimap<String, Double> transformed = Multimaps.transformValues(multimap, sqrt);
   * System.out.println(transformed);
   * }
   *
   * ... prints {@code {a=[2.0, 4.0], b=[3.0]}}.
   *

   *
   * {@snippet :
   * ListMultimap<String, Integer> multimap = ImmutableListMultimap.of("a", 4, "a", 16, "b", 9);
   * Function<Integer, Double> sqrt = (Integer in) -> Math.sqrt((int) in);
   * ListMultimap<String, Double> transformed = Multimaps.transformValues(multimap, sqrt);
   * System.out.println(transformed);
   * }
   *
   * ... prints {@code {a=[2.0, 4.0], b=[3.0]}}.
   *

    assertEquals(ImmutableSet.of(1, 2, 3), bimap.inverse().keySet());
    assertEquals(ImmutableSet.of(1, 2, 3), sync.inverse().keySet());
  }

  private static final Function<Integer, Double> SQRT_FUNCTION = in -> Math.sqrt(in);

  public void testTransformValues() {
    Map<String, Integer> map = ImmutableMap.of("a", 4, "b", 9);
    Map<String, Double> transformed = transformValues(map, SQRT_FUNCTION);