code: public static <T> CloseableIterable<T> concat(final CloseableIterable<? extends Iterable<? extends T>> inputs) {
          return wrap(Iterables.concat(inputs), inputs);
      }
docs: Combines multiple iterables into a single closeable iterable.
  The returned closeable iterable has an iterator that traverses the elements
  of each iterable in {@code inputs}. The input iterators are not polled until
  necessary.