I assume this works but I thought `this` meant something special in observable. See this nb, which says "this is the previous value of the current cell": https://observablehq.com/@mbostock/sticky-views

Interesting. This does work, which makes me think that the way Observable is set up is that each cell is an object that can be accessed from within the cell, or some such variation on that. Observable seems to be cleverly programmed enough to recognize when `this` is being used in the context of an object and not the cell, as I have see other Object method definitions using `this` across Observable. It would seem that Observable allows both uses of `this` (see https://observablehq.com/@tmcw/untitled/5 and https://observablehq.com/@amazingdesign/object-creation). Interesting to think about though. Hm...