argtree

Create a fully-functional command-line utility named 'TaskMaster' using the Python package 'argtree'. This utility will help users manage their daily tasks efficiently. It should allow users to add, delete, update, and view their tasks. Each task should have a title, description, due date, and priority level (low, medium, high). Additionally, users should be able to categorize tasks into different categories such as 'Work', 'Home', 'Personal', etc.

The application should support subcommands for each action (add, delete, update, view), and it should validate user inputs to ensure that all required fields are filled out correctly before processing the commands. For example, when adding a new task, the user must provide a title and a due date at minimum.

Use 'argtree' to define these command structures and input validations. Show how 'argtree' simplifies the creation of complex command-line interfaces by allowing you to declare your command structure as a dataclass or NamedTuple tree. Demonstrate how you can use type hints within 'argtree' to enforce strong typing on command line arguments, making it easier to handle different types of data like dates and priorities.

Additionally, implement a feature where users can export their task lists to a JSON file and import them back into TaskMaster. This should also utilize 'argtree' to handle file paths and other necessary parameters.

Provide a brief explanation and code snippets for each step of implementing 'argtree' in your application, highlighting its benefits over traditional argparse.