AsyncGenerator functions for API Pagination

[danopia]

There is some choice of style here:

1. Do the funcs yield each page's response in its entirety?
2. Do the funcs yield each inner item individually, hiding the page concept?
3. Should both styles be implemented for extra flexibility?

My instinct is that it's pretty easy to write a custom loop if visibility of the full pages are required, so the convenience functions should hide the pages. But I could be convinced otherwise I think.