in app/lib/primer/class_name_helper.rb [8:27]
def class_names(*args)
[].tap do |classes|
args.each do |class_name|
case class_name
when String
classes << class_name if class_name.present?
when Hash
class_name.each do |key, val|
classes << key if val
end
when Array
classes << class_names(*class_name).presence
end
end
classes.compact!
classes.uniq!
end.join(" ")
end