scala> import collection.mutable._
import collection.mutable._
scala> val buf = new ListBuffer[Int]
buf: scala.collection.mutable.ListBuffer[Int] = ListBuffer()
scala> buf += 22
res0: scala.collection.mutable.ListBuffer[Int] = ListBuffer(22)
scala> buf ++= List(1, 2, 3)
res1: scala.collection.mutable.ListBuffer[Int] = ListBuffer(22, 1, 2, 3)
scala> buf.toList
res2: scala.collection.immutable.List[Int] = List(22, 1, 2, 3)
scala> :quit