Map a Vega-Lite mark type to the Vega CSS class used in the rendered SVG.
Vega-Lite marks are not Vega marks: the compiler rewrites several of them
(a tick is a narrow Vega rect), and a composite mark expands into
a group per part, of which only one carries the values a reader
navigates. That part is what this names — the whip of an errorbar, the
band of an errorband — so the class returned is the one that holds one
element per sample.
Map a Vega-Lite mark type to the Vega CSS class used in the rendered SVG.
Vega-Lite marks are not Vega marks: the compiler rewrites several of them (a
tickis a narrow Vegarect), and a composite mark expands into a group per part, of which only one carries the values a reader navigates. That part is what this names — the whip of anerrorbar, the band of anerrorband— so the class returned is the one that holds one element per sample.