Added Comments in periodic.py – Based on PR #140

[SophiaLi20]

Hey ,
I’ve added comments to periodic.py to make the code easier to understand and maintain. These updates align with the changes made in PR #140. Since I had forked the repository earlier, a new PR wasn’t automatically created, but you can check my changes by referring to PR #140.
What I Did:

• Added clear and structured comments to explain key functions.
• Documented how data structures work to make the logic easier to follow.
• Ensured that my comments align with the improvements introduced in PR Improved argument parsing and error handling in __main__.py #140.

Why This Helps:

• Easier to Read – Future contributors won’t have to spend extra time figuring things out.
• Better Collaboration – Anyone jumping in can quickly understand the code.
• Smoother Debugging – Clear documentation makes troubleshooting simpler.
• Long-term Maintainability – Well-documented code stays useful for a long time.