Apply trexfeathers/cf-units#8 `demo_1.py` improvements to `templates/demo_1.py`?

[trexfeathers]

trexfeathers/cf-units#8 (by @trexfeathers) includes changes to demo_1.py. This file is templated by templates/demo_1.py. Please either:

• Action this issue with a pull request applying the changes to templates/demo_1.py.
• Close this issue if the changes are not suitable for templating.