input: Write a python function to check if a given string is a palindrome using a class.
  assert Palindrome("level").is_palindrome() == True
  assert Palindrome("world").is_palindrome() == False
  assert Palindrome("radar").is_palindrome() == True
output: class Palindrome:
      def __init__(self, s):
          self.s = s
  
      def is_palindrome(self):
          return self.s == self.s[::-1]