Fix undefined names in Python `demo` files #189

Job	Run time
python_sdist	7s
make_linux_matrix	9s
make_windows_matrix	4s
make_macos_matrix	4s
macos (cp313-macosx_x86_64, macos-13)	8m 26s
macos (cp313-macosx_arm64, 11.0, arch -arm64 bash --noprofile --norc -eo pipefail {0})	3m 46s
windows (cp313-win_amd64)	1m 34s
linux (cp313-manylinux_x86_64)	4m 35s
linux (cp313-musllinux_x86_64)	4m 33s
merge_artifacts	3s
check	2s
	23m 23s

Provide feedback