code: def _define_event(callback_function):
      available_events[callback_function.__name__] = callback_function
      return callback_function
  
file_path: catboost/contrib/python/ipython/py3/IPython/core/events.py
label_desc: Use image node_id 1 for calling a global function with example usage: _define_event(callback_function) and returns: callback_function