fix: add detailed inline comments to improve code readability (#80)

[htang085]

Description

This branch addresses feedback provided in Issue #80. Specifically, it:

• Adds detailed inline comments to improve the readability of the save_data.py function.
• Clarifies the purpose of each step in the code (e.g., directory validation, error handling, and file saving).

Related Issue

Fixes #80

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (83c890c) to head (4f6e4b3).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #84   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            4         4           
  Lines           57        57           
=========================================
  Hits            57        57           

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[lixuanlinjam]

Looks good!! a lot of details get fixed!