MagicalMeghan

<!-- Copyright 2019 Google LLC. 
   SPDX-License-Identifier: Apache-2.0 -->

val choir = Choir()
val singerMeghan = Singer("Meghan")
choir += singerMeghan

MagicalMeghan

<!-- Copyright 2019 Google LLC. 
   SPDX-License-Identifier: Apache-2.0 -->
   
data class Singer(val name: String) 
fun main() {
    val choir = Choir()
    val singerMeghan = Singer("Meghan")
    choir += singerMeghan
    if(singerMeghan in choir){
        println("Meghan is a part of the choir!")

MagicalMeghan

<!-- Copyright 2019 Google LLC. 
   SPDX-License-Identifier: Apache-2.0 -->

operator fun contains(s: Singer) : Boolean {
       return singers.contains(s)
}

MagicalMeghan

<!-- Copyright 2019 Google LLC. 
   SPDX-License-Identifier: Apache-2.0 -->

data class Singer(val name: String) 

fun main() {
    val choir = Choir()
    val singerMeghan = Singer("Meghan")
    
    choir += singerMeghan

MagicalMeghan

<!-- Copyright 2019 Google LLC. 
   SPDX-License-Identifier: Apache-2.0 -->

class Choir {
    private val singers = mutableListOf<Singer>()

    operator fun plusAssign(singer: Singer) {        
        singers.add(singer)
    }
}

MagicalMeghan

<!-- Copyright 2019 Google LLC. 
   SPDX-License-Identifier: Apache-2.0 -->

class Choir {
    private val singers = mutableListOf<Singer>()

    fun addSinger(singer: Singer) {
        singers.add(singer)
    }