Questions

1. How do you define a class in Kotlin?
2. How do you define an interface in Kotlin?
3. What are data classes?
4. What are sealed classes?
5. How is a sealed class different from an enum?
6. What is an object expression?
7. What is an object declaration?

8. What is a companion object?
9. What are the four visibility modifiers in Kotlin?
10. What are the differences between a primary and a secondary constructor?