code: @CheckReturnValue
      public final FluentIterableWrapper<E> append(Iterable<? extends E> other) {
          return from(Iterables.concat(iterable, other));
      }
docs: Returns a fluent iterable whose iterators traverse first the elements of this fluent iterable,
  followed by those of {@code other}. The iterators are not polled until necessary.
  
  <p>The returned iterable's {@code Iterator} supports {@code remove()} when the corresponding
  {@code Iterator} supports it.