ImmutableMap

object ImmutableMap {

  def merge[A, B](m1: Map[A, B], m2: Map[A, B]): Map[A, B] = {
    var m3: Map[A, B] = m1 //Store new map in m3
    if (m1.isEmpty) {
      m3 = m2 //Return m2 if m1 is empty
    }
    else {
      for (key <- m2.keys) { //Iterate over keys and check values
        if (m1.contains(key)) {
          sys.error(f"Key Duplicate! $key exists in both Maps!")
        } else { //Add to map if key is free
          m3 += (key -> m2(key))
        }
      }
    }
    m3
  }
}