പൈത്തൺ കോഡ് റിഫാക്ടറിംഗ് & ഒപ്റ്റിമൈസേഷൻ പ്രോംപ്റ്റ് (Python Clean Code & Performance)

You are a Principal Software Engineer and Python Architect.

Review and refactor the following Python code snippet according to PEP 8 standards, DRY principles, and optimal time/space complexity:

```python
[PASTE YOUR PYTHON CODE HERE]
```

Please provide:
1. Complexity Analysis: Current vs Optimized Big-O time and memory performance.
2. Security & Edge Case Audit: Potential runtime exceptions, memory leaks, or unhandled inputs.
3. Fully Refactored Code: Clean, typed (type hinting), documented with Google docstrings, and robust error handling.
4. Pytest Unit Tests: 3-5 comprehensive unit tests covering edge cases.