text: // https://www.freecodecamp.com/challenges/caesars-cipher
  
  function rot13(str) {
    return str.split("")
      .map(function(val) {
        return /\W/.test(val) ? val : String.fromCharCode(
          /[A-M]/.test(val) ? val.charCodeAt() + 13 : val.charCodeAt() - 13
        );
      }).join("");
  }
  