/**
 * Converts an {@link ApolloStoreOperation} to a Single.
 *
 * @param operation the ApolloStoreOperation to convert
 * @param <T>       the value type
 * @return the converted Single
 */
@NotNull
@CheckReturnValue
public static <T> Single<T> from(@NotNull final ApolloStoreOperation<T> operation) {
  checkNotNull(operation, "operation == null");
  return Single.create(new SingleOnSubscribe<T>() {
    @Override
    public void subscribe(final SingleEmitter<T> emitter) {
      operation.enqueue(new ApolloStoreOperation.Callback<T>() {
        @Override
        public void onSuccess(T result) {
          emitter.onSuccess(result);
        }

        @Override
        public void onFailure(Throwable t) {
          emitter.onError(t);
        }
      });
    }
  });
}
 

public static <T> Single<T> createDefault(@NonNull SingleOnSubscribe<T> singleOnSubscribe) {
    return create(singleOnSubscribe).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread());
}