After reading instructions, complete required steps: Your task is to implement a linked dictionary, which will store key-value pairs in a linked list.

Your linked dictionary should support the following operations:

add(key, value): Adds a new key-value pair to the linked dictionary. If the key already exists, the corresponding value should be updated.

get(key): Returns the value associated with the given key, or None if the key does not exist.

delete(key): Deletes the key-value pair with the given key from the linked dictionary.

You should implement the linked dictionary using the class LinkedDict.

The linked dictionary should store its elements in a linked list.

Implement the linked list using a separate class Node.

Do not use any built-in data structures in Python, such as dictionaries, lists, or sets.

Write test cases for each method to ensure that the code is working as expected.