No module named 'torch._six'

This error typically occurs when there is a version mismatch between PyTorch and other dependent packages. Here are some steps you can try to resolve the issue:

1. Check that you have the latest version of PyTorch installed. You can do this by running `pip install torch -U`.

2. Try uninstalling and reinstalling PyTorch. You can do this by running `pip uninstall torch` followed by `pip install torch`.

3. Check that you have the latest version of other dependent packages installed. You can do this by running `pip install -r requirements.txt`.

4. If you just upgraded PyTorch, restart your Python interpreter or Jupyter Notebook.

5. If none of the above steps work, you may need to uninstall and reinstall all dependent packages.