[Kotlin] Exercise for Map

fun main(args: Array<String>) {
   val ipToCount = mutableMapOf<String, Int>()
   File("src/ips.txt").forEachLine {
       val previous = ipToCount.getOrDefault(it, 0)
       ipToCount.put(it, previous + 1)
   }
   
   // get max count ip
   val (maxIp, maxCount) = ipToCount.entries.maxBy {
       it.value
   }!!
}