class_docstr: Simple event to which event handlers can be attached. For instance::
  
      class Cls:
          def __init__(self):
              # Define event. The first parameter is the sender.
              self.event = Event(self)
  
      obj = Cls()
  
      def handler(sender):
          pass
  
      # Add event handler by using the += operator.
      obj.event += handler
  
      # Fire event.
      obj.event()
docstr: Remove a handler from this callback.
code: def remove_handler(self, handler: Callable[[_Sender], None]) -> None:
      """
      Remove a handler from this callback.
      """
      if handler in self._handlers:
          self._handlers.remove(handler)
  
imports: from __future__ import annotations
  import os
  import signal
  import sys
  import threading
  from collections import deque
  from typing import Callable, ContextManager, Dict, Generator, Generic, TypeVar, Union
  from wcwidth import wcwidth
label_desc: Use image node_id 5 for calling the Event obj's underlying member method code with example usage: obj.remove_handler(handler) without return types