DISCUSSION

This code implements an expiry tracker for products using CSV files. Let's break down the code and discuss its components.

Libraries and Frameworks:
1. `glob` library is used to find files matching a specified pattern.
2. `argparse` library is used for parsing command-line arguments.
3. `csv` library is used for reading and writing CSV files.
4. `os` library provides various operating system-related functionalities.
5. `datetime` module provides classes for manipulating dates and times.
6. `tabulate` library is used to generate formatted tables.

Design Patterns:
1. The code follows the object-oriented programming (OOP) paradigm, organizing related functionality into classes and methods.
2. The code uses the static method implementation for the `ErrorMessage` class, providing reusable error messages.

Logic Flow:
1. The code defines an `ErrorMessage` class to handle and display error messages.
2. The `ExpiryTracker` class is defined, representing the main functionality of the expiry tracker.
3. The `ExpiryTracker` class contains methods to load shelf life data, calculate expiration dates, append data to history and expiry report, generate expiry reports, clear expired entries, clear history file, and print tables.
4. The `run` method in the `ExpiryTracker` class handles the main logic based on the command-line arguments.
5. The `main` function uses the `argparse` library to parse command-line arguments and create an instance of `ExpiryTracker`.
6. Depending on the command-line arguments, the `main` function either runs the expiry tracker for a single CSV file or processes multiple files in a batch.

Trends and Libraries:
1. The code uses standard libraries like `csv` and `os` to handle CSV file operations and operating system functionalities, respectively.
2. The `argparse` library is commonly used for handling command-line arguments in Python applications.
3. The code uses the `tabulate` library to generate formatted tables, which can be helpful for visualizing data.

Overall, the code implements an expiry tracker that can process individual CSV files or multiple files in a batch. It provides functionality to calculate expiration dates, append data to history and expiry reports, generate reports based on expiration thresholds, clear expired entries, clear history file, and print tables. The code follows OOP principles and utilizes several standard libraries to achieve its functionality efficiently.