work with streams

[rullyalves]

thank you for the quality of your library, I would like to know if there is interest in implementing the subscribe so that it returns a Stream instead of using callbacks.
I would be willing to raise a PR for this.

[KammererTob]

Hey. That sounds like a great idea. I think we should make the callback optional at first and deprecate it slowly instead of immediatly removing it. Or what do you think?

[ch-muhammad-adil]

This one looks helpful, but right now having your own stream object can solve problem.