constructor

public class ConsDemo {
   public static void main(String args[]) {
      MyClass t1 = new MyClass();
      MyClass t2 = new MyClass();
      System.out.println(t1.num + " " + t2.num);
   }
}

class Person {
    var children: MutableList<Person> = mutableListOf<>()
    constructor(parent: Person) {
        parent.children.add(this)
    }
}