input: Write a function to determine if a given string is a palindrome. Convert the string to lowercase and then compare characters from the start and end towards the center. If all characters match, return True; otherwise, return False. If the string is empty, it should return True.
  assert is_palindrome("racecar")==True
  assert is_palindrome("hello")==False
  assert is_palindrome("A man a plan a canal Panama")==True
  assert is_palindrome("")==True
  assert is_palindrome("Never odd or even")==True
output: def is_palindrome(s):
      s = s.lower().replace(" ", "")
      return s == s[::-1]