question: Accessing the best validation loss so far in validation_epoch_ends
context: How can I access the best validation loss in validation_epoch_end?  I am assuming the loss is stored somewhere as it is used to save the best model based on it, so I was wondering if I can somehow directly access it instead of tracking it my self.
answer: I think if you include a ModelCheckpoint in your trainer, you should be able to retrieve the best model score. But you should set your validation loss as the monitored variable in your ModelCheckpoint callback. From your validation_epoch_end, you should be able to retrieve your best score by reaching the callback with something similar to self.trainer.callback.best_model_score.