Documenting some functions and methods that are difficult to understand.

[scovl]

Description

Documenting some functions and methods that are difficult to understand. I feel that the atomic project codes lack some lines of comments to facilitate future contributions. I'm working on it.

Pull Request Checklist:

If your Pull request contains new features or functions, tests are required. If the PR is a bug fix and no tests exist, please consider adding some to prevent regressions.

• [ ] Unittests
• [ ] Integration Tests

[scovl]

I will make the considerations and add some other necessary comments. Thank's!