* {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the minus sign.
   *
   * <p>Unlike {@link Double#parseDouble(String)}, this method returns {@code null} instead of
   * throwing an exception if parsing fails. Valid inputs are exactly those accepted by {@link
   * Double#valueOf(String)}, except that leading and trailing whitespace is not permitted.
   *

   * {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the minus sign.
   *
   * <p>Unlike {@link Float#parseFloat(String)}, this method returns {@code null} instead of
   * throwing an exception if parsing fails. Valid inputs are exactly those accepted by {@link
   * Float#valueOf(String)}, except that leading and trailing whitespace is not permitted.
   *

    when the URL is malformed instead of returning null. Use this to avoid checking for null in
    situations where the input is known to be well-formed. We've also added `MediaType.get(String)`
    which is an exception-throwing alternative to `MediaType.parse(String)`.
 *  New: The `EventListener` API previewed in OkHttp 3.9 has graduated to a stable API. Use this
    interface to track metrics and monitor HTTP requests' size and duration.

   * {@code '-'} (<code>'&#92;u002D'</code>) is recognized as the minus sign.
   *
   * <p>Unlike {@link Double#parseDouble(String)}, this method returns {@code null} instead of
   * throwing an exception if parsing fails. Valid inputs are exactly those accepted by {@link
   * Double#valueOf(String)}, except that leading and trailing whitespace is not permitted.
   *

   * fromElement}. However, this method doesn't throw an exception in that situation, but instead
   * keeps the original {@code fromElement}. Similarly, this method keeps the original {@code
   * toElement}, instead of throwing an exception, if passed a {@code toElement} greater than an
   * earlier {@code toElement}.
   */
  @Override
  public ImmutableSortedSet<E> subSet(E fromElement, E toElement) {

    @Override
    public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {}
  }

  /**
   * A CyclicBarrier that uses timed await and fails with AssertionFailedErrors instead of throwing
   * checked exceptions.
   */
  public class CheckedBarrier extends CyclicBarrier {
    public CheckedBarrier(int parties) {
      super(parties);
    }

    @Override

        /*
         * We can't just return the iterator because an immediate call to its
         * remove() method would remove one of the skipped elements instead of
         * throwing an IllegalStateException.
         */
        return new Iterator<T>() {
          boolean atStart = true;

          @Override
          public boolean hasNext() {
            return iterator.hasNext();

REGISTER_OP("TestNonCommUnavailable")
    .Output("out: string")
    .Doc(R"doc(Test non-communication op throwing Unavailable error.)doc");

REGISTER_OP("TestCommUnavailable")
    .Output("out: string")
    .SetIsDistributedCommunication()
    .Doc(R"doc(Test communication op throwing Unavailable error.)doc");

// Kernel that throws an Unavailable error.
class TestUnavailableErrorOp : public tensorflow::OpKernel {

          }

          @Override
          public String toString() {
            return function.toString();
          }
        };
    // TODO(dpb): Switch to future.transformSync when that exists (passing a throwing function).
    return derive(future.transformAsync(applyFunction, executor));
  }

  /**
   * Returns a new {@code ClosingFuture} pipeline step derived from this one by applying a function

   * fromElement}. However, this method doesn't throw an exception in that situation, but instead
   * keeps the original {@code fromElement}. Similarly, this method keeps the original {@code
   * toElement}, instead of throwing an exception, if passed a {@code toElement} greater than an
   * earlier {@code toElement}.
   */
  @Override
  public ImmutableSortedSet<E> subSet(E fromElement, E toElement) {