The shinyWidgets gallery

Let's look at all the different input options that are already built for you by exploring the shinyWidgets package. It comes with a neat built-in function, shinyWidgetsGallery() that opens a pre-built Shiny app that allows you to explore these pre-built inputs and gives you the code for implementing them.

Navigate to the radioButtons section. What argument do you use in radioGroupButtons() to display the buttons vertically instead of horizontally?