} catch (Throwable t) {
        threadUnexpectedException(t);
      }
    }
  }

  public abstract class CheckedCallable<T> implements Callable<T> {
    protected abstract T realCall() throws Throwable;

    @Override
    public final T call() {
      try {
        return realCall();
      } catch (Throwable t) {
        threadUnexpectedException(t);
        return null;
      }
    }