# File lib/new_relic/agent/transaction.rb, line 117
      def self.start(state, category, options)
        category ||= :controller
        txn = state.current_transaction

        if txn
          txn.create_nested_frame(state, category, options)
        else
          txn = start_new_transaction(state, category, options)
        end

        txn
      rescue => e
        NewRelic::Agent.logger.error("Exception during Transaction.start", e)
        nil
      end