Docs don't give an example on how to fully use pagination.

It only has an example of doing a listing with page=1, per_page=10

Is there a way, for example, to know ahead of time how many pages there will be?

For example I'm calling gl.project_issues.list(project_id=project.id, per_page=10, page=n)
By incrementing n beyond the actual number of pages I see that I don't get an exception of any kind, instead just empty lists.

I only found that out by digging into it. I don't see it documented anywhere.