public <T extends @Nullable Object> T[] toArray(T[] array) {
      return Lists.newArrayList(iterator()).toArray(array);
    }
  }

  /**
   * Returns a collection that applies {@code function} to each element of {@code fromCollection}.
   * The returned collection is a live view of {@code fromCollection}; changes to one affect the
   * other.
   *

    public <T extends @Nullable Object> T[] toArray(T[] array) {
      return Lists.newArrayList(iterator()).toArray(array);
    }
  }

  /**
   * Returns a collection that applies {@code function} to each element of {@code fromCollection}.
   * The returned collection is a live view of {@code fromCollection}; changes to one affect the
   * other.
   *