Generate lists of regions that we use for various tasks.
regions(type)
The name of a region type; must be one of "all", "england", or "nations"
A character vector
sircovid::regions("england")
#> [1] "east_of_england" "london"
#> [3] "midlands" "north_east_and_yorkshire"
#> [5] "north_west" "south_east"
#> [7] "south_west"