code: @Beta
    public final FluentIterable<E> append(Iterable<? extends E> other) {
      return FluentIterable.concat(getDelegate(), 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.
  
  <p><b>{@code Stream} equivalent:</b> {@link Stream#concat}.
  
  @since 18.0