Fix TBPTT example

[lantiga]

What does this PR do?

Fixes #20517

Thanks to @simon-bachhuber for the fix

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📚 Documentation preview 📚: https://pytorch-lightning--20528.org.readthedocs.build/en/20528/

[github-actions]

⚡ Required checks status: All passing 🟢

Groups summary

🟢 pytorch_lightning: Tests workflow

Check ID	Status
pl-cpu (macOS-14, lightning, 3.9, 2.1, oldest)	success	✅
pl-cpu (macOS-14, lightning, 3.10, 2.1)	success	✅
pl-cpu (macOS-14, lightning, 3.11, 2.2.2)	success	✅
pl-cpu (macOS-14, lightning, 3.11, 2.3)	success	✅
pl-cpu (macOS-14, lightning, 3.12.7, 2.4.1)	success	✅
pl-cpu (macOS-14, lightning, 3.12.7, 2.5.1)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.9, 2.1, oldest)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 2.1)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.11, 2.2.2)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.11, 2.3)	success	✅
pl-cpu (ubuntu-22.04, lightning, 3.12.7, 2.4.1)	success	✅
pl-cpu (ubuntu-22.04, lightning, 3.12.7, 2.5.1)	success	✅
pl-cpu (windows-2022, lightning, 3.9, 2.1, oldest)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 2.1)	success	✅
pl-cpu (windows-2022, lightning, 3.11, 2.2.2)	success	✅
pl-cpu (windows-2022, lightning, 3.11, 2.3)	success	✅
pl-cpu (windows-2022, lightning, 3.12.7, 2.4.1)	success	✅
pl-cpu (windows-2022, lightning, 3.12.7, 2.5.1)	success	✅
pl-cpu (macOS-14, pytorch, 3.9, 2.1)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.9, 2.1)	success	✅
pl-cpu (windows-2022, pytorch, 3.9, 2.1)	success	✅
pl-cpu (macOS-14, pytorch, 3.12.7, 2.5.1)	success	✅
pl-cpu (ubuntu-22.04, pytorch, 3.12.7, 2.5.1)	success	✅
pl-cpu (windows-2022, pytorch, 3.12.7, 2.5.1)	success	✅

These checks are required after the changes to tests/tests_pytorch/helpers/advanced_models.py, tests/tests_pytorch/helpers/test_models.py.

🟢 pytorch_lightning: Azure GPU

Check ID	Status
pytorch-lightning (GPUs) (testing Lightning | latest)	success	✅
pytorch-lightning (GPUs) (testing PyTorch | latest)	success	✅

These checks are required after the changes to tests/tests_pytorch/helpers/advanced_models.py, tests/tests_pytorch/helpers/test_models.py.

🟢 pytorch_lightning: Docs

Check ID	Status
docs-make (pytorch, doctest)	success	✅
docs-make (pytorch, html)	success	✅

These checks are required after the changes to docs/source-pytorch/common/tbptt.rst.

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Thank you for your contribution! 💜

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[Borda]

could we also add a test for it?

[t-vi]

@Borda given that it is in the example, wouldn't it be in the doc build (or in a bit of code that cannot be run on the CI due to being too large)?

[lantiga]

Actually, I would like this to be a copy-pastable example, which this isn't. More work to be done.

[lantiga]

Alright, I made it correct and runnable.

[lantiga]

I added the corresponding test, it's very lightweight

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79%. Comparing base (efe311c) to head (fb9e836).
Report is 45 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (efe311c) and HEAD (fb9e836). Click for more details.

HEAD has 144 uploads less than BASE

Flag	BASE (efe311c)	HEAD (fb9e836)
cpu	70	35
lightning	50	28
pytest	33	0
python3.9	18	9
python3.11	21	11
python3.10	9	4
lightning_fabric	11	0
python3.12.7	22	11
pytorch2.1	14	13
pytest-full	37	35
pytorch2.2.2	9	6
pytorch_lightning	9	7

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #20528     +/-   ##
=========================================
- Coverage      87%      79%     -8%     
=========================================
  Files         267      264      -3     
  Lines       23380    23325     -55     
=========================================
- Hits        20235    18366   -1869     
- Misses       3145     4959   +1814     

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[Borda]

Looks good :)