input: Write a python function to check if a string is a palindrome.
  assert isPalindrome('Madam') == True
  assert isPalindrome('Racecar') == True
  assert isPalindrome('Hello') == False
  assert isPalindrome('A man a plan a canal Panama') == False
output: def isPalindrome(s):
      s = s.lower()
      return s == s[::-1]