How to use the libmozevent.mercurial.MercurialWorker function in libmozevent

self.bus.add_queue(QUEUE_PULSE_BUGBUG_TEST_SELECT, redis=True)
            self.bus.add_queue(QUEUE_PULSE_TRY_TASK_END, redis=True)
            self.bus.add_queue(QUEUE_WEB_BUILDS, redis=True)

        # Run work processes on worker dyno or single instance
        if not heroku.in_dyno() or heroku.in_worker_dyno():
            self.workflow = CodeReview(
                api_key=taskcluster_config.secrets["PHABRICATOR"]["api_key"],
                url=taskcluster_config.secrets["PHABRICATOR"]["url"],
                publish=publish,
                user_blacklist=taskcluster_config.secrets["user_blacklist"],
            )
            self.workflow.register(self.bus)

            # Build mercurial worker and queue
            self.mercurial = MercurialWorker(
                QUEUE_MERCURIAL,
                QUEUE_MERCURIAL_APPLIED,
                repositories=self.workflow.get_repositories(
                    taskcluster_config.secrets["repositories"],
                    cache_root,
                    default_ssh_key=taskcluster_config.secrets["ssh_key"],
                ),
            )
            self.mercurial.register(self.bus)

            # Setup monitoring for newly created tasks
            self.monitoring = Monitoring(
                taskcluster_config,
                QUEUE_MONITORING,
                taskcluster_config.secrets["admins"],
                MONITORING_PERIOD,