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
maven-dependency-check-plugin
rticles
quick-score
domain-name
android-compose-card
coingecko-api
model-associations
ubiquity
tokenize
substrate
terraform-provider-azure
pocketpc
ddx
formatdatetime
objective-function
victory-native
static-linking
readability
search-engine-bots
primeicons
django-custom-user
package.json
azure-cognitive-services
android-filterable
xcode13.3.1
facebooksdk.net
rebar
google-oauth
version
buffer-overflow
