Add hello_world.py with Hello World function

[Eric-Flecher-Glean]

Description

This PR adds a new file hello_world.py containing a simple Hello World function.

Changes:

• Added hello_world.py with a hello_world() function that returns "Hello World"
• Included a docstring for the function
• Added a main block to run the function when the script is executed directly

Testing

Run the script:

python hello_world.py

Expected output: Hello World

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