input: Write a function to check if a given string is a palindrome by converting it to lowercase and comparing the string from both ends. If the string is a palindrome, return True, otherwise return False. If the string is empty, return True.
  assert is_palindrome("racecar")==True
  assert is_palindrome("level")==True
  assert is_palindrome("hello")==False
  assert is_palindrome("A man a plan a canal Panama")==False
  assert is_palindrome("")==True
output: def is_palindrome(s):
      s = s.lower()
      return s == s[::-1]