* Multimap<String, String> transformed =
   *     Multimaps.transformEntries(multimap, transformer);
   * System.out.println(transformed);
   * }
   *
   * ... prints {@code {"a"=["a1", "a4"], "b"=["b6"]}}.
   *
   * <p>Changes in the underlying multimap are reflected in this view. Conversely, this view
   * supports removal operations, and these are reflected in the underlying multimap.
   *