code: function clearEvent(emitter, evt) {
    if (--emitter._eventsCount === 0) emitter._events = new Events();
    else delete emitter._events[evt];
  }
docs: Clear event by name.
  
  @param {EventEmitter} emitter Reference to the `EventEmitter` instance.
  @param {(string|Symbol|number)} evt The Event name.
  @private