I have: A = {a, b, c, d, e} I want to write: B = {a, b, c, d, e, f, g} But I don't want to write duplicate code So I write: B = B(A) = {A, e, f, g

I have: A = {a, b, c, d, e} I want to write: B = {a, b, c, d, e, f, g} But I don't want to write duplicate code So I write: B = B(A) = {A, e, f, g} aka I use inheritance. Are there easier ways? No. Inheritance is the most fundamental way of doing this. Composition is just a work around as it results in arbitrary nesting. But ultimately it's the same thing too.