go =>

  S = "123456789",
  println(S),
  S := "A" ++ S,
  println(S),

  % append
  append("B",S,T),
  S := T,
  println(S),

  % insert at position
  S := insert(S,1,'C'), % note: must be a char to keep it a proper string
  println(S),
  % insert many characters
  S := insert_all(S,1,"DE"),
  println(S),
  nl.