use `andThen` to compose functions

fromScalaConsole.scala

import scala.io.Source.stdin

object App {
  def main(args: Array[String]) {
    stdin.getLines foreach { line =>
      println(myconvert(line.toInt))
    }
  }
  
  val double = (number:Int) => 2*number
  val add10 = (number:Int) => 10 + number
  val negative = (number:Int) => -1 * number
  
  val mod0 = negative andThen double andThen add10
  val mod1 = add10 andThen  negative andThen double
  val mod2 = add10 andThen double andThen negative

  def myconvert(n:Int) = {
    n%3 match {
      case 0 => mod0(n) 
      case 1 => mod1(n)
      case 2 => mod2(n)
    }
  }
  
}