A palindrome is a word, phrase, number, or other sequence of characters which reads the same backwards and forwards. For example, "racecar" and "A man, a plan, a canal: Panama" are palindromes, while "hello" is not. Your task is to write a function, is_palindrome(s) that takes in a string and returns a Boolean value indicating whether the string is a palindrome. The function should ignore any non-alphanumeric characters and be case-insensitive, meaning that the function should treat upper and lower case letters the same. Your solution should use recursion. Any solutions that use loops or map/filter will receive no credit. Examples: is_palindrome("A man, a plan, a canal: Panama") True is_palindrome(" r a c e car") True is_palindrome("122 1") True is_palindrome("121") True is_palindrome("hello") False is_palindrome("122") False Stub: def is_palindrome(s: str) bool