def urbanmain() = {
  import M2._


  assert(removeN(List(1,2,3,2,1), 3, 1)  == List(1, 2, 2, 1))
  assert(removeN(List(1,2,3,2,1), 2, 1)  == List(1, 3, 2, 1))
  assert(removeN(List(1,2,3,2,1), 1, 1)  == List(2, 3, 2, 1))
  assert(removeN(List(1,2,3,2,1), 0, 2)  == List(1, 2, 3, 2, 1))
  assert(removeN(List("a", "b", "b"), "b", 1) == List("a", "b"))
  assert(removeN(List("b", "a", "b", "b"), "b", 2) == List("a", "b"))
  assert(removeN(List("b", "a", "b"), "a", 2) == List("b", "b"))

  //assert(removeOne(List(1,2,3,2,1), 3) == List(1, 2, 2, 1))
  //assert(removeOne(List(1,2,3,2,1), 2) == List(1, 3, 2, 1))
  //assert(removeOne(List(1,2,3,2,1), 1) == List(2, 3, 2, 1))
  //assert(removeOne(List(1,2,3,2,1), 0) == List(1, 2, 3, 2, 1))
}