code: def get_listener_manager() -> ListenerManager:
      """Get singleton listener manager."""
      global _listener_manager
      if not _listener_manager:
          _listener_manager = ListenerManager()
          integrate_listener_plugins(_listener_manager)
      return _listener_manager
  
file_path: airflow/airflow/listeners/listener.py
imports: from __future__ import annotations
  import logging
  from typing import TYPE_CHECKING
  import pluggy
  from airflow.plugins_manager import integrate_listener_plugins
label_desc: Use image node_id 1 for calling a global function with example usage: get_listener_manager() and returns: _listener_manager