Improvements to demo_helmholtz.py and demo_scattering_boundary_conditions.py

[RequieMa]

Delete an unused variable in demo_helmholtz.py
Add a description for clarity in demo_scattering_boundary_conditions.py

[francesco-ballarin]

@BillMaZengou please have a look at GitHub actions status that you see below your message, for instance https://github.com/FEniCS/dolfinx/actions/runs/7551811797/job/20559652794?pr=2992.

You'll find that they are failing because of a flake8 check: try to fix the whitespace issue and add a new commit with your change.

[RequieMa]

Yes. Sorry for that. The white space was not clear in my IDE.
I found a way to delete it. However, I am not sure how to push the change again in this PR...

[RequieMa]

@BillMaZengou please have a look at GitHub actions status that you see below your message, for instance https://github.com/FEniCS/dolfinx/actions/runs/7551811797/job/20559652794?pr=2992.

You'll find that they are failing because of a flake8 check: try to fix the whitespace issue and add a new commit with your change.

It seems that it is automatically updated.

Briefly document my steps for future reference (as it is quite difficult to notice whitespace in some IDEs, e.g. Jupyter):

• pip install pylint or pip install flake8 to install
• pylint <file> or flask8 <file> for checking the format issue
• add nnoremap <F5> :let _s=@/<Bar>:%s/\s\+$//e<Bar>:let @/=_s<Bar><CR> in ~/.vimrc
• open file with vim and solve the whitespace issue by simply pressing F5 key

https://vi.stackexchange.com/questions/454/whats-the-simplest-way-to-strip-trailing-whitespace-from-all-lines-in-a-file

[francesco-ballarin]

Thanks @BillMaZengou, this has now been queued for merge by @jorgensd . We may be switching soon to ruff for formatting (instead of flake8), so you may have to slightly change the steps in the first two bullets at some point in the future.

[RequieMa]

Thanks @BillMaZengou, this has now been queued for merge by @jorgensd . We may be switching soon to ruff for formatting (instead of flake8), so you may have to slightly change the steps in the first two bullets at some point in the future.

Thanks! I will research the format. I did not pay attention to those format before. It has been a good practice for me