return !queue.isEmpty();
    }

    @Override
    @ParametricNullness
    public T next() {
      PeekingIterator<T> nextIter = queue.remove();
      T next = nextIter.next();
      if (nextIter.hasNext()) {
        queue.add(nextIter);
      }
      return next;
    }
  }

  private static class ConcatenatedIterator<T extends @Nullable Object> implements Iterator<T> {

      return !queue.isEmpty();
    }

    @Override
    @ParametricNullness
    public T next() {
      PeekingIterator<T> nextIter = queue.remove();
      T next = nextIter.next();
      if (nextIter.hasNext()) {
        queue.add(nextIter);
      }
      return next;
    }
  }

  private static class ConcatenatedIterator<T extends @Nullable Object> implements Iterator<T> {

    // yield.
    SmallVector<Value, 4> new_results(old_num_operands);
    int next_idx = 0;
    for (int op_idx : llvm::seq<int>(0, old_num_operands))
      if (!removed_operand.test(op_idx))
        new_results[op_idx] = new_while_op.getResult(next_idx++);

    rewriter.replaceOp(while_op, new_results);
    return success();
  }
};

}  // anonymous namespace

  auto b = ops::Placeholder(root.WithOpName("B"), DT_FLOAT);
  auto c = ops::Add(root.WithOpName("C"), a, b);
  auto enter = ops::internal::Enter(root, c, "aframe");
  auto next_iter = ops::NextIteration(root, enter);
  auto exit = ops::internal::Exit(root, next_iter);
  auto d = ops::Add(root.WithOpName("D"), c, exit);

  std::unique_ptr<Graph> graph(new Graph(OpRegistry::Global()));
  TF_EXPECT_OK(root.ToGraph(graph.get()));

ng++]=e}function h(t,e){t.pending_buf[t.pending++]=e>>>8&255,t.pending_buf[t.pending++]=255&e}function d(t,e,a,i){var n=t.avail_in;return n>i&&(n=i),0===n?0:(t.avail_in-=n,z.arraySet(e,t.input,t.next_in,n,a),1===t.state.wrap?t.adler=S(t.adler,e,n,a):2===t.state.wrap&&(t.adler=E(t.adler,e,n,a)),t.next_in+=n,t.total_in+=n,n)}function f(t,e){var a,i,n=t.max_chain_length,r=t.strstart,s=t.prev_length,o=t.nice_match,l=t.strstart>t.w_size-it?t.strstart-(t.w_size-it):0,h=t.window,d=t.w_mask,f=t.prev,_=t...