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
dockerfile-maven-plugin
ssml
footnotes
reconciliation
glove
nested-set-model
adaboost
post-commit
kafka-consumer-api
ant
eventvalidation
system.numerics.vectors
drag-and-drop
xctestexpectation
anchor
parcel
hmacsha512
jenkins-job-dsl
subclassing
callscreeningservice
character-properties
wazuh
kerberos
queryselectall
client-side-validation
formatted
null-terminated
azure-alerts
react-functional-component
nodeenv
