FunctionReferences3.kt

fun main() {
    val classOne = ClassOne()
    val classTwo = ClassTwo()
    
    classTwo.myFunc(true, classOne::doSomething)
}

class ClassOne {
    private val output = "Hello, world!!!"
    
    fun doSomething() {
        println(output)
    }  
}

class ClassTwo {
    fun myFunc(someCondition: Boolean, funcRef: () -> Unit) {
        if (someCondition) {
            funcRef()
        }
    }
}