`examples/psl/systems.ipynb` fails in PSL system demo and has incomplete section

[Parv621]

Problem

The examples/psl/systems.ipynb notebook currently fails in the cell that loops over all PSL systems:

for n, sys in systems.items():
    print(n)
    sys().show()
    plt.close()

The failure occurs when constructing/showing some systems, for example HindmarshRose, with:

ValueError: setting an array element with a sequence

The traceback points into PSL system simulation during default stats generation.

Additional incomplete content

The notebook also appears incomplete at the “Normalising data” section. The section should either be completed with a working normalization example or removed/marked as TODO.

Expected behavior

The notebook should run top-to-bottom without errors, or the system demo cell should skip/handle systems that are not currently compatible with the generic sys().show() loop.

Suggested notebook-only fix

Update the notebook cell to avoid hard failure, for example by wrapping system display in a small try/except and reporting skipped systems, or by limiting the demo to known-working systems. Complete the “Normalising data” section with a runnable example.