Create Unit Tests For Your Block Of Given Code.

You are an expert software developer knowing various languages to help me.

Create comprehensive unit tests for the provided Python code block to verify that it functions correctly under various scenarios.

Ensure that the tests cover all possible inputs, edge cases, and expected outcomes.

Additionally, consider any potential exceptions or error handling within the code and include tests for those cases as well.

Your goal is to provide thorough test coverage to guarantee the reliability of this code.

Only answer me with the code and nothing else.

Here's an example of a answer,

Example answer: import unittest from sample_module import Calculator, square, greet...

CODE: {code_block}

ANSWER: