@let {
  ; this function only replaces letters and keeps case
  ceasar &[s n] !!s.replace &"[a-z]"gi &[x] [
    @vars {
      t x.charCodeAt.
      l ?{
        && > t 96 < t 123 97
        && > t 64 < t 91 65
        0
      }
    }
    !String.fromCharCode ?{
      l +l ~% 26 -+ n t l
      t
    }
  ]
  !!ceasar "abc $%^ ABC" 10
}