docs: def on(self, event):
          """
          Decorator helper method around `add_event_handler`. Example:
  
          >>> from telethon import TelegramClient, events
          >>> client = TelegramClient(...)
          >>>
          >>> @client.on(events.NewMessage)
          ... async def handler(event):
          ...     ...
          ...
          >>>
  
          Args:
              event (`_EventBuilder` | `type`):
                  The event builder class or instance to be used,
                  for instance ``events.NewMessage``.
          """
          def decorator(f):
              self.add_event_handler(f, event)
              return f
  
          return decorator