Add postprocess_with_star_set! and postprocess_with_tree_set!

[amontoison]

The goal of this PR is to make the "diff" in #267 more readable.
I just created two functions postprocess_with_star_set! and postprocess_with_tree_set!.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (85e2d05) to head (297e2ca).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #279   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           20        20           
  Lines         1997      2005    +8     
=========================================
+ Hits          1997      2005    +8     

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