May be how the concrete `Map` class you're using i...

# getting-started

[paulblessing]

May be how the concrete Map class you're using is implemented then. This works fine:

val map = mutableMapOf<Pair<String, Any>, Any>()
map["5" to "a"] = "a"
map["5" to "b"] = "b"
map["3" to "q"] = "q"
map.keys.removeAll { it.first == "5" }
println(map)