object Main {
 
  def main(args: Array[String]) {
    val secret = List('3', '_', 'r', '@', '!', '?', 'a')
 
    // Just a Map from Char to Char
    val key = Map(
        '@' -> 'a',
        'x' -> 'y',
        '?' -> 'm',
        '4' -> 't',
        '3' -> 'e', 
        'r' -> 'p')
 
    val decoded: List[Char] = for { // let's yield (build) a new list
      x <- secret	// let x iterate on Chars of the List secret
      y <- key get x    // let y be the value looked up in the Map (if exists, otherwise skip)
    } yield y.toUpper   // append y uppercased to the List we are building
 
    val collected = decoded.mkString // join the Chars to form a String
 
    for {
      // sliding(2) returns an iterator over sliding windows of length 2 the string
      // zipWithIndex transforms the iterator to yield (A, index) instead just A, for some type A
      // so slice is a String of length 2
      (slice, i) <- collected.sliding(2).zipWithIndex
    } println(" " * i + slice) // print the string slice "animated"
 
  }
 
}

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