gauge_* family of functions is similar to
scale_* though there are some stark differences in places.
See motif vignette for examples of built-in color palettes.
You can gauge aspects specific aspects, just like in ggplot2.
htmlwidgets::JS, the function must accept as argument the aspect variable used.
To use a variable as gauge (e.g.: size, or color) and hide the legend pass a boolean to the appropriate