delete duplicate objects of list / 重複したリストのオブジェクトを削除したい

deleteDuplicates.kt

data class User(val name : String, val latLng: LatLng)

data class LatLng(val lat: Int, val lng: Int)

fun deleteDuplicates() {
   // create data
    val results = (1..10).map {User("$it", LatLng(it % 4, it%4))}
    results.forEach {
	    println(it)    
    }
    println()
    
    // grouping by latlng
    val r2 = results.groupingBy { it.latLng }
  
    // delete duplicate objects
    val r3 = r2.reduce { key, accumulator, element ->
            if(accumulator.latLng == element.latLng) {
			       accumulator             
            } else  element
    }
    println()
    r3.forEach {
        println(it)
    }
    println()
    
    r3.values.forEach {
        println(it)
    }
    
}