data class User(val id: Int, val email: String) {
	var firstname: String? = null
	var lastname: String? = null
}

fun main(args: Array<String>) {
    val user1 = User(1, "admin@admin.com")
	user1.firstname = "John"
	user1.lastname = "Wick"

	println("${user1.firstname} ${user1.lastname}")
	// Result is "John Wick"

	val user2 = user1.copy()
	println("${user2.firstname} ${user2.lastname}")
	// Result is null null
}