pets += "rob" -> "dog"

import scala.collection.mutable;

object SolutionXX extends Application {

val pets = mutable.Map("joe" -> "cat", "mary" -> "turtle", "bill" -> "canary")

pets += "rob" -> "dog"

println(pets.size)
for ((k : String, v : String) <- pets) { printf("%s : %d\n", k, v) }
}