def urbanmain() = {
  import M2._

  assert(score("chess", "caves") == List(Correct, Absent, Absent, Present, Correct))
  assert(score("doses", "slide") == List(Present, Absent, Absent, Present, Present))
  assert(score("chess", "swiss") == List(Absent, Absent, Absent, Correct, Correct))
  assert(score("chess", "eexss") == List(Present, Absent, Absent, Correct, Correct))

  val urban_p = pool("chess", "caves")

  assert(aux("chess".toList, "caves".toList, Nil) == List(Correct, Absent, Absent, Absent, Correct))
  assert(aux("chess".toList, "caves".toList, urban_p) == List(Correct, Absent, Absent, Present, Correct))
}