Nested JSON to CSV Converter

I'm in immediate need of assistance to build a Python function that converts a nested JSON file to a CSV formatted file, in line with my given specifications. The subsequent CSV should match an example I will provide. The function should be compatible to work with any JSON file of the same data structure.

Skills and Experience Required:
- Proficiency in Python
- Experience in handling JSON and CSV files
- Ability to understand and follow provided specifications

Deliverables:
- A Python function that successfully converts nested JSON to specified CSV format
- Documentation explaining how to use the function

Timeline:
- The project needs to be completed ASAP. Prompt delivery is greatly appreciated.