I'm trying to make a formula and I got the error: $ operator not defined for this S4 class with R. First of all, what is a S4 class? What am I doing wrong
iinterceptor
baseweb
surveytogo
vignette
showtext
rosetta
react-native-camera
syndication
zcat
immutability-helper
mach
angular-custom-validators
verify
lz77
ng-grid
taglib
swiftui-swipeactions
mutability
git-squash
keystonejs
self-attention
react-refresh-webpack-plugin
uicomponents
complextype
title
django-import-export-celery
react-lifecycle-hooks
swiftui-contextmenu
parcel
image-resolution
