PyTorch torchVision Object Detection finetuning tutorial

I am from Taiwan so my English is not very good !
I practicing the TorchVision Object DeteCtion Finetuning Tutorial on PyTorch
but I encountered an error that says 'module ‘email.utils’ has no attribute ‘collate_fn’."
Because I imported collat_fn, but I still got an error when debugging.
I’m not sure what to do.
Thanks to everyone for their answers.
If anyone needs my code, you can leave a message below."

It seems the email.utils module does not provide the collate_fn method so make sure you are using the right module and check if you would have a namespace conflict.
I.e. could you explain where exactly your collate_fn is defined?

I define my collate_fn in
Below is my screenshot

This is my code, and if anybody finds any errors, please let me know. Thank you, everyone!