scala> import com.github.nscala_time.time.Imports._
import com.github.nscala_time.time.Imports._

scala> implicit class DurationHelper(d:org.joda.time.Duration) {
     | def toScalaDuration = scala.concurrent.duration.Duration.apply(d.getMillis,scala.concurrent.duration.MILLISECONDS)
     | }
defined class DurationHelper

scala> val d = RichInt(3).seconds.toDuration
// toDuration method is defined for com.github.nscala_time.time.DurationBuilder
d: org.joda.time.Duration = PT3S

scala> def exfun(d:scala.concurrent.duration.Duration) = d.toString
exfun: (d: scala.concurrent.duration.Duration)String

scala> exfun(d)
res41: String = 3000 milliseconds