2.) Basic Kotlin Features

typed nullability

smart casting (and mutable vars gotcha)

lateinit vars

properties, backing fields (set(value) { field = value ... }, difference between val x = "" and val x: String get() = ""

string interpolation and """multiline escaped ${strings}"""

data classes

null safety operators: safe-call (?.) and elvis (?:)

when keyword (and complex conditions, such as ranges)

control statement as expression (assignment of when, return, ...)

vararg and the * spread operator

interfaces and default implementation

generics (<T: Blah>, in/out, and star projection <*>)