Issues with examples: untested or outdated

Issues with examples: untested or couldn't run

Example 23 is untested, meaning that any changes to naming convention may go unnoticed in Example 23 since its not tested in test_all_examples.py

Additionally, some examples have their own plotting or post-processing code in the run script that is not included in the test. This means that some examples that can be run successfully in test_all_examples.py, would not be able to be run successfully from the command line:

cd examples/03_methanol/co2_hydrogenation_doc
python run_co2h_methanol.py # this would result in an error when this script calls `plot_methanol`
# ValueError: The units 't/day' are invalid 

I think this could cause confusion for users and should be fixed.

I think that this should be addressed with the larger example refactor effort.

Start with test_all_examples.py and the Example 23 coverage, then inspect examples/03_methanol/co2_hydrogenation_doc/run_co2h_methanol.py and its plot_methanol call. Check which plotting or post-processing steps are omitted from the test path. Done means the affected examples are tested and their command-line run scripts complete successfully.