src/transformers/trainer_callback.py/CallbackHandler/pop_callback
class CallbackHandler:    def pop_callback(self, callback):
        if isinstance(callback, type):
            for cb in self.callbacks:
                if isinstance(cb, callback):
                    self.callbacks.remove(cb)
                    return cb
        else:
            for cb in self.callbacks:
                if cb == callback:
                    self.callbacks.remove(cb)
                    return cb