input: Write a python function to check if a given string is a palindrome.
  assert is_palindrome("Madam")=="yes, this is a palindrome"
  assert is_palindrome("Hello")=="no, this is not a palindrome"
  assert is_palindrome("Racecar")=="yes, this is a palindrome"
output: def is_palindrome(s):
      s = s.lower().replace(" ", "")
      if s == s[::-1]:
          return "yes, this is a palindrome"
      else:
          return "no, this is not a palindrome"