What kind of object i get with input$checkboxGroupInput in shiny?

Question

I want to do a TA dashboard in shiny and i wish to plot each indicator checked from the checkboxGroupInput the problem is when using input$my_checkboxGroupInput I don't know what kind of object it is or how to compare it with strings (technical indicators), my idea was to use case_when() and if the string is checked then do the line to plot it with quantmod.

something like this:

 case_when(
       "Volume" %in% input$my_checkboxGroupInput  ~ addVo(),
       "SMA" %in% input$my_checkboxGroupInput  ~ addSMA(),
       TRUE ~ NA
    )

But it doesn't work so i suspect input$my_checkboxGroupInput is not a string vector, then what is it?