A rule that takes place after all conversation quips have been exhausted

Hi, I am using Threaded Conversations to encode some basic conversation.
I have a list of quips that the player can inquiry about.
I want to do something after all the quips have been requested. For instance, to automatically end the conversation and say good bye.
I cannot find any reference to something like this in the docs. Could you give me some advice?

Do you mean something like the following?

Last Every turn when the current interlocutor is someone and the number of entries in the list of available quips is zero:
    try leavetaking.

That seems useful enough that Iā€™d like to see it become part of the extension.