In this project, you will build BiblioTech, a command-line library management system that lets librarians manage a catalog of books and digital media, track whether items are available or checked out, and calculate overdue fines based on return dates.

This project applies the intermediate Python concepts from Modules 7–14, including object-oriented programming (OOP), custom exceptions, file I/O, and generators, to build a structured application. Starting with an abstract base design, you will implement polymorphic behavior, structured error handling using custom exceptions, and JSON-based persistence for storing application data to produce a working application with persistent storage.