class Foo {
    def parse(list: List[String]) = list match {
        case "a" :: xs => 1
        case "b" :: Nil => 2
        case ("c" | "d") :: xs => 3
        case "1" :: "2" :: "3" :: Nil => 4
        case "1" :: "2" :: "3" :: xs => 5
        case x :: xs => 6
        case Nil => 7
    }
}