Question about speaker interpolation in Fastpitch
Hi, thanks for the great work!
I saw the recently added speaker interpolation tutorial and decided to have a try.

Sometime ago I followed the `FastPitch_Finetuning.ipynb` tutorial and mixed a small dataset with a big dataset and did the finetuning with `n_speakers=2`. This model can be used to do speaker interpolation, is that right?

The speaker interpolation tutorial says `Choose new_speaker ID such that it is not already assigned to an existing speaker` and in [fastpitch.py](https://github.com/NVIDIA/NeMo/blob/a74f262dbd39aff9d7ec3c12c9322c3a4036a97c/nemo/collections/tts/models/fastpitch.py#L687-691) it says `the new_speaker_id should be less than the total number of speakers`.

So in my case, speaker 0, 1 have been assigned, and `n_speakers=2`. How should I set the `new_speaker` ID?

Thank you!