*/
  @CanIgnoreReturnValue
  public static boolean retainAll(Iterable<?> removeFrom, Collection<?> elementsToRetain) {
    return (removeFrom instanceof Collection)
        ? ((Collection<?>) removeFrom).retainAll(checkNotNull(elementsToRetain))
        : Iterators.retainAll(removeFrom.iterator(), elementsToRetain);
  }

  /**

   * Returns a string containing all non-matching characters of a character sequence, in order. For
   * example:
   *
   * {@snippet :
   * CharMatcher.is('a').removeFrom("bazaar")
   * }
   *
   * ... returns {@code "bzr"}.
   */
  public String removeFrom(CharSequence sequence) {
    String string = sequence.toString();
    int pos = indexIn(string);
    if (pos == -1) {
      return string;
    }

   * Returns a string containing all non-matching characters of a character sequence, in order. For
   * example:
   *
   * {@snippet :
   * CharMatcher.is('a').removeFrom("bazaar")
   * }
   *
   * ... returns {@code "bzr"}.
   */
  public String removeFrom(CharSequence sequence) {
    String string = sequence.toString();
    int pos = indexIn(string);
    if (pos == -1) {
      return string;
    }

    }
    assertEquals(-1, matcher.lastIndexIn(""));
    assertFalse(matcher.matchesAnyOf(""));
    assertTrue(matcher.matchesAllOf(""));
    assertTrue(matcher.matchesNoneOf(""));
    assertThat(matcher.removeFrom("")).isEqualTo("");
    assertThat(matcher.replaceFrom("", 'z')).isEqualTo("");
    assertThat(matcher.replaceFrom("", "ZZ")).isEqualTo("");
    assertThat(matcher.trimFrom("")).isEqualTo("");