add simple zn.nodes example

[PythonFZ]

• add more text to the example and clean up

[codecov]

Codecov Report

Merging #545 (c22e1c8) into main (e4479cb) will increase coverage by 0.47%.
The diff coverage is n/a.

❗ Current head c22e1c8 differs from pull request most recent head 3704220. Consider uploading reports for the commit 3704220 to get more accurate results

@@            Coverage Diff             @@
##             main     #545      +/-   ##
==========================================
+ Coverage   89.42%   89.90%   +0.47%     
==========================================
  Files          21       19       -2     
  Lines        1560     1228     -332     
  Branches      601      441     -160     
==========================================
- Hits         1395     1104     -291     
+ Misses        165      123      -42     
- Partials        0        1       +1     

Flag	Coverage Δ
fulltest	88.43% <ø> (-0.99%)	⬇️

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see 13 files with indirect coverage changes

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