AsyncCallable<T> task =
        new AsyncCallable<T>() {
          @Override
          public ListenableFuture<T> call() throws Exception {
            if (!taskExecutor.trySetStarted()) {
              return immediateCancelledFuture();
            }
            return callable.call();
          }

          @Override
          public String toString() {

    AsyncCallable<T> task =
        new AsyncCallable<T>() {
          @Override
          public ListenableFuture<T> call() throws Exception {
            if (!taskExecutor.trySetStarted()) {
              return immediateCancelledFuture();
            }
            return callable.call();
          }

          @Override
          public String toString() {