OkHttp nested requests

gistfile1.txt

    // this is a singleton and it takes instance from dagger!
    @Inject OkHttpClient client;
    Subscription sub;

    @Override
    protected void onDestroy() {
        super.onDestroy();
        // Stop the request if our activity/fragment has been destroyed.
        if (sub != null && !sub.isUnsubscribed()) {
            sub.unsubscribe();
        }
    }

    public void insideSomeFunction() {
        sub = chainableRequests()
            .subscribe(new Action1<String>() {
                @Override
                public void call(String resultFromMultipleRequests) {
                    myTextView.setText(resultFromMultipleRequests);
                }
            }, new Action1<Throwable>() {
                @Override
                public void call(Throwable throwable) {
                    Toast.makeText(getBaseContext(), "error during our request:" +
                        throwable.getMessage(), Toast.LENGTH_SHORT).show();
                }
            });

    }

    public Observable<String> chainableRequests() {
        return getHello() // execute the first request
            .flatMap(new Func1<String, Observable<String>>() {
                @Override
                public Observable<String> call(String helloString) {
                    // get the result from the first request and pass it to the second
                    return doSomethingWithTheHello(helloString);
                }
            })
            // Go outside of the main thread in order to prevent ANR
            .subscribeOn(Schedulers.io())
            //  Once everything is finished go back to main thread.
            .observeOn(AndroidSchedulers.mainThread());
    }

    public Observable<String> getHello() {
        return Observable.create(new Observable.OnSubscribe<String>() {
            @Override
            public void call(Subscriber<? super String> subscriber) {
                if (subscriber.isUnsubscribed()) {
                    return;
                }
                try {
                    Request request = new Request.Builder()
                        .url("http://publicobject.com/helloworld.txt")
                        .build();

                    Response response = client.newCall(request).execute();
                    if (!response.isSuccessful())  {
                        subscriber.onError(new Throwable("Unexpected code " + response));
                    } else {
                        subscriber.onNext(response.body().string());
                        subscriber.onCompleted();
                    }
                } catch (IOException error) {
                    subscriber.onError(error);
                }
            }
        });
    }

    public Observable<String> doSomethingWithTheHello(String hello) {
        return Observable.create(new Observable.OnSubscribe<String>() {
            @Override
            public void call(Subscriber<? super String> subscriber) {
                if (subscriber.isUnsubscribed()) {
                    return;
                }
                try {
                    MediaType textType = MediaType.parse("text/html; charset=utf-8");
                    Request request = new Request.Builder()
                        .url("https://api.github.com/markdown/raw")
                        .post(RequestBody.create(textType, hello))
                        .build();

                    Response response = client.newCall(request).execute();
                    if (!response.isSuccessful())  {
                        subscriber.onError(new Throwable("Unexpected code " + response));
                    } else {
                        subscriber.onNext(response.body().string());
                        subscriber.onCompleted();
                    }
                } catch (IOException error) {
                    subscriber.onError(error);
                }
            }
        });
    }