Python: Improve docstrings and output formatting

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.

Project coverage is 90.98%. Comparing base (83a6680) to head (a80f331). Report is 2 commits behind head on master.

Files	Patch %	Lines
python/src/exactextract/operation.py	90.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #149 +/- ## ========================================== - Coverage 90.98% 90.98% -0.01% ========================================== Files 85 85 Lines 6358 6368 +10 Branches 627 627 ========================================== + Hits 5785 5794 +9 - Misses 541 542 +1 Partials 32 32 ```

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