Propositional Logic Prover I project has been updated

Hello everyone,

I want to announce that Propositional Logic Prover I project had an update. The update is most importantly about overriding the __str__ method of the WFF class instead of creating a to_string method for each subclass. Furthermore, the string is generated at instantiation and then stored in an attribute. Other modifications include better rephrasing certain paragraphs and adding further details for clarity.

By the way, the next phase of the project will soon be available. We will use the parser to generate a truth table given a well-formed formula. I hope you find it interesting and useful!

Thank you for your attention, and please feel free to reach out if you have any questions or feedback!