given (x: Array[Char]) extended with {
  inline def swap(i: Int, j: Int) : Unit =
    val v = x(i)
    x(i)  = x(j)
    x(j)  = v
}
val a = Array('A','B')
a.swap(0,1)
println(a.toList)
// Run Result
List(B, B)
// Expectation
List(B, A)
If "inline" is removed, the expectation is fulfilled