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encapsulation. three ways are public, private and protected. can be used as keywords above the method definitions, or can be used as protected :method_name. protected can be accessed by other members of the same class, private doesn't allow that
polymorphism example
learning about nested classes, need to play with it a bit more as the current output from the code is not something that i expected; heading to dinner now.
rough demonstrates a way to print the fibonacci nos
the benefits of modules to avoid confusion among classes/methods/constants with same names.
mix ins allow us to add useful features from one class to another
experimenting with modules