text: function rot13(str) {
    let alpha = "ABCDEFGHIJKLM NOPQRSTUVWXYZ";
    let new_str = ""
    for (let i = 0; i < str.length; i++){
      if (str[i].length === 1 && str[i].match(/[a-z]/i)) {
        let indx_alpha = alpha.indexOf(str[i]);
        if (indx_alpha > alpha.indexOf('M')){
          new_str += alpha[indx_alpha - 14];
        } else {
          new_str +=  alpha[indx_alpha + 14];
        }
      } else {
        new_str += str[i]
      }
    }
    
    return new_str;
  }
  