# File lib/new_relic/agent/instrumentation/evented_subscriber.rb, line 13
        def self.subscribed?
          # TODO: need to talk to Rails core about an API for this,
          # rather than digging through Listener ivars
          ActiveSupport::Notifications.notifier.instance_variable_get(:@subscribers) \
            .find{|s| s.instance_variable_get(:@delegate).class == self }
        end