# File lib/new_relic/agent/instrumentation/controller_instrumentation.rb, line 229
          def self.prefix_for_category(txn, category = nil)
            category ||= (txn && txn.category)
            case category
            when :controller    then ::NewRelic::Agent::Transaction::CONTROLLER_PREFIX
            when :task          then ::NewRelic::Agent::Transaction::TASK_PREFIX
            when :rack          then ::NewRelic::Agent::Transaction::RACK_PREFIX
            when :uri           then ::NewRelic::Agent::Transaction::CONTROLLER_PREFIX
            when :sinatra       then ::NewRelic::Agent::Transaction::SINATRA_PREFIX
            when :middleware    then ::NewRelic::Agent::Transaction::MIDDLEWARE_PREFIX
            when :grape         then ::NewRelic::Agent::Transaction::GRAPE_PREFIX
            when :rake          then ::NewRelic::Agent::Transaction::RAKE_PREFIX
            when :action_cable  then ::NewRelic::Agent::Transaction::ACTION_CABLE_PREFIX
            else "#{category.to_s}/" # for internal use only
            end
          end