// If 'supertype' is "List<? extends CharSequence>"
      // and 'this' is StringArrayList,
      // First step is to figure out StringArrayList "is-a" List<E> where <E> = String.
      // String is then matched against <? extends CharSequence>, the supertypeArgs[0].
      if (!of(subtypeParam).is(supertypeArgs[i], typeVars[i])) {
        return false;
      }
    }

   */
  public static Splitter on(char separator) {
    return on(CharMatcher.is(separator));
  }

  /**
   * Returns a splitter that considers any single character matched by the given {@code CharMatcher}
   * to be a separator. For example, {@code
   * Splitter.on(CharMatcher.anyOf(";,")).split("foo,;bar,quux")} returns an iterable containing
   * {@code ["foo", "", "bar", "quux"]}.
   *

   * the given predicate, if such an element exists.
   *
   * <p><b>Warning:</b> avoid using a {@code predicate} that matches {@code null}. If {@code null}
   * is matched in this fluent iterable, a {@link NullPointerException} will be thrown.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.filter(predicate).findFirst()}.
   */

   * given predicate, if such an element exists.
   *
   * <p><b>Warning:</b> avoid using a {@code predicate} that matches {@code null}. If {@code null}
   * is matched in {@code iterable}, a NullPointerException will be thrown.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.filter(predicate).findFirst()}
   *
   * @since 11.0
   */

   * the original {@code ClosingFuture} instance.
   *
   * @param exceptionType the exception type that triggers use of {@code fallback}. The exception
   *     type is matched against this step's exception. "This step's exception" means the cause of
   *     the {@link ExecutionException} thrown by {@link Future#get()} on the {@link Future}

   * hasNext()} method will return {@code false}.
   *
   * <p><b>Warning:</b> avoid using a {@code predicate} that matches {@code null}. If {@code null}
   * is matched in {@code iterator}, a NullPointerException will be thrown.
   *
   * @since 11.0
   */
  public static <T> Optional<T> tryFind(Iterator<T> iterator, Predicate<? super T> predicate) {
    checkNotNull(iterator);

   * the given predicate, if such an element exists.
   *
   * <p><b>Warning:</b> avoid using a {@code predicate} that matches {@code null}. If {@code null}
   * is matched in this fluent iterable, a {@link NullPointerException} will be thrown.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code stream.filter(predicate).findFirst()}.
   */

   * hasNext()} method will return {@code false}.
   *
   * <p><b>Warning:</b> avoid using a {@code predicate} that matches {@code null}. If {@code null}
   * is matched in {@code iterator}, a NullPointerException will be thrown.
   *
   * @since 11.0
   */
  public static <T> Optional<T> tryFind(Iterator<T> iterator, Predicate<? super T> predicate) {
    checkNotNull(iterator);