refactor some setter getter methods using the property decorator

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It's the most pythonic way I found to create safe setters and getters for a property: https://www.programiz.com/python-programming/property

[12rambau]

some extra explainantion on the why: https://python.plainenglish.io/should-you-use-getters-and-setters-in-python-d4db9a892878