[O] Beamer export: toggle export of select headlines/frames

[Vikas Rawal]

I am creating a beamer presentation, but want to be able to toggle inclusion or 
exclusion of some headlines/frames in the export, depending on the occasion 
where the presentation is being made. What is the appropriate way to do this?

I can use :no export: for selected headlines, but it would have been useful if 
I could have an easy way to switch.

Vikas