input: Write a python function to find the next largest palindrome number.
  assert next_largest_palindrome("1234") == 1331
  assert next_largest_palindrome("808") == 818
  assert next_largest_palindrome("999") == 1001
output: def next_largest_palindrome(n):
      def is_palindrome(s):
          return s == s[::-1]
  
      num = int(n) + 1
      while not is_palindrome(str(num)):
          num += 1
      return num