Remove confusing comma in Coroutines Hands-on

[SebastianAigner]

This change makes sure the sentence reflects the actual meaning: We're switching to the type of API that uses callbacks, rather than switching to the API, which incidentally happens to use callbacks.

[dkhalanskyjb]

I don't understand it. The sentence is about switching to a particular API, called Retrofit, which mitigates the problem by using callbacks instead of blocking. Am I missing something?

[SebastianAigner]

It's precisely not about switching to an API called Retrofit. The previous example also uses the Retrofit API. This sentence specifically talks about the part of the Retrofit API that happens to use callbacks.

In other words, we're switching "[from the blocking Retrofit API] to the callback-based Retrofit API".

[dkhalanskyjb]

Ah, yes, you're right! Sorry for the noise.