input: Write a function to determine if a given string is a palindrome. A palindrome is a string that reads the same forward and backward. The function should convert the string to lowercase, and then check if the string is the same from the start to the end and end to the start. If it is a palindrome, return True, otherwise return False.
  assert is_palindrome("racecar")==True
  assert is_palindrome("hello")==False
  assert is_palindrome("Madam")==True
  assert is_palindrome("level")==True
  assert is_palindrome("Python")==False
output: def is_palindrome(s):
      s = s.lower()
      return s == s[::-1]