First caller adds a prompt to queue and
        runs followers until there are no more
        pending prompts.

        Subsequent callers just add a prompt
        to the queue, avoiding recursion.

def run_followers(self, prompt):
        """
        First caller adds a prompt to queue and
        runs followers until there are no more
        pending prompts.

        Subsequent callers just add a prompt
        to the queue, avoiding recursion.
        """
        assert isinstance(prompt, Prompt)
        # Put the prompt on the queue.
        self.pending_prompts.put(prompt)

        if self.iteration_lock.acquire(False):
            start_time = time.time()
            i = 0
            try:
                while True:
                    try:
                        prompt = self.pending_prompts.get(False)
                    except Empty:
                        break
                    else:
                        followers = self.system.followers[prompt.process_name]
                        for follower_name in followers:
                            follower = self.system.processes[follower_name]
                            follower.run(prompt)
                            i += 1
                        self.pending_prompts.task_done()
            finally:
                run_frequency = i / (time.time() - start_time)
                # print(f"Run frequency: {run_frequency}")
                self.iteration_lock.release()