Improve printing of rational number

[blegat]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.58%. Comparing base (ba3697f) to head (26ae5d3).
⚠️ Report is 70 commits behind head on main.

Files with missing lines	Patch %	Lines
src/show.jl	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #58      +/-   ##
==========================================
- Coverage   86.26%   85.58%   -0.68%     
==========================================
  Files          14       14              
  Lines         757      763       +6     
==========================================
  Hits          653      653              
- Misses        104      110       +6     

Flag	Coverage Δ
unittests	85.58% <0.00%> (-0.68%)	⬇️

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[kalmarek]

There's lots of code related to printing, but it is hardly tested.