code: def remove_callback(self, instance, func):
          
          for cb in [self._callbacks, self._2arg_callbacks]:
              if instance not in cb:
                  continue
              if func in cb[instance]:
                  cb[instance].remove(func)
                  return
          else:
              raise ValueError("Callback function not found: %s" % func)
docs: Remove a previously-added callback
  
          Parameters
          ----------
          instance
              The instance to detach the callback from
          func : func
              The callback function to remove