Chapter 13 ch13_part3_lightning. ipynb is missing (def validation_step)

[Le-Thi-Ngoc-Trang-1209]

An error occurred: " ValueError: .test(ckpt_path="best") is set but ModelCheckpoint is not configured to save the best model. " when I run file ch13_part3_lightning.ipynb.

There seems to be an error when you copy MultiLayerPerceptron class from file ch13_part3_lightning.py to file ch13_part3_lightning.ipynb. MultiLayerPerceptron of File ch13_part3_lightning.py still has block (def validation_step) but file ch13_part3_lightning.ipynb doesn't.