Docs

Added new docstings and changes to some files

added 4 commits

• b2ab3707...37fc78e5 - 3 commits from branch release-5.3
• 2a410245 - Merge branch 'release-5.3' into 'docs'

Compare with previous version

assigned to @dmitry.puzyrkov

mentioned in commit 60a65d8f

merged