is_palindrome.py

def is_palindrome(word, i=0):
    """Is word a palindrome?

        >>> is_palindrome("noon")
        True

        >>> is_palindrome("tacocat")
        True

        >>> is_palindrome("zacbz")
        False
    """

    # winning base case: reach middle of word
    if i >= len(word) // 2:
        return True

    if word[i] != word[-i-1]:
        return False

    return is_palindrome(word, i + 1)