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object WhileLoop {

  @tailrec
  def whileLoop(b: => Boolean, command: => Unit): Unit  = {
    if (b) {
      (command);
      whileLoop(b, command)
    } else ()
  }

  def main(args: Array[String]): Unit = {
    val mas = Array(1, 2, 3)
    var i = 0
    whileLoop(i < mas.length, { println(i); i += 1 })
  }
}