Hi @fil, in order to understand and test all functionality (which I forked on my side) I tried to use `show_equator` and `show_structure` but I do not see any effects. Am I missing something? Also on `keepcanvas`, what is the aim? Thanks & ciao

I've now updated the notebook to demonstrate these options. I had used show_structure to show how polyhedral projections are constructed, but the option wasn't exposed. Same for the equator. The keepcanvas option was for when I needed a demo in which I would not clear the canvas from one frame to the other. These were all clandestine options, that I just enabled when I needed them. Note also that they are only available in the canvas mode, because I was lazy and didn't duplicate all the code for svg. (I don't have big plans for this notebook, I'll be focusing more on Plot.carto instead, because it solves a lot of issues such as specifying different data-based layers, creating a legend, having sensible defaults for color scales &c.)

Thanks! Looking forward to using Plot.carto and all love and great effort/expertise you put in it.