[TM-111] Refactorings 2

Description

Some common refactorings expected long ago.

Related issue(s)

https://issues.serokell.io/issue/TM-111

✅ Checklist for your Merge Request

Related changes (conditional)

• Tests (see short guidelines)

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.

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    • README
    • Haddock
    • docs/
  • I updated the changelog if my changes are externally visible.

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