• The s variable conditionally defined was never used.
• The '--latex' in sys.argv branch (which dates back to the origin of
  the example, a567601), likely never worked (\mathbb requires
  \usepackage{amsfonts}), so just kill it.
• Saving the figure doesn't really help with the example and tends to
  clutter the source tree when running the example, so don't do it.

PR Summary

PR Checklist

• Has Pytest style unit tests
• Code is PEP 8 compliant
• New features are documented, with examples if plot related
• Documentation is sphinx and numpydoc compliant
• Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
• Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way