The main goal of this exercise was to understand the pattern chosen and create a practical example.

So, we used the Chain of Responsibility that contemplates a chain where each part is responsible for maintaining operation. When a request coming from the client, it will pass for this chain - e.g. client request send an e-mail so will be examined and execute in one of the steps.

To better exemplify, below we show a diagram of how this is working.

We did a simple code that show what happens when it's buying a product and applied different discounts.

Check here the code and UML: Apply different discounts code

I had problems to organizer the code in folders. My tests were put in subfolders, so when I tried to do an import from a parent folder or another folder, I received this error:

    ModuleNotFoundError: No module named [name file]

To resolve I used to bash and type this command on root folder:

    export PYTHONPATH="$PWD"

Some refs.: scratch file