code: function isPalindrome(s) {
      var total = s.length;
      if(total < 2) return true;
      if(s.charAt(0) !== s.charAt(total - 1)) return false;
  
      return isPalindrome(s.substr(1, total - 2));
  }
docs: ## isPalindrome(a)  Returns `true` if `a` is a valid palindrome.