'NoneType' object is not iterable error

I scored 0/50 in the function train_happy_sad_model please help me to score 50/50 by solving my error.

[code removed - moderator]

Please check notebook metadata and refresh the workspace if required / in doubt. If that doesn’t help, click my name and message your notebook as an attachment.

Here’s the error message lifted right from your notebook: Use ‘accuracy’ as metric when compiling your model.

@balaji.ambresh Thanks . I have scored 100/100 .