#
# check for palindromes
#
def palin(s):
    # base case: empty string
    if s == "":
        return True
    # recursive case
    # 1. see if the first and last letter
    #    are the same; if not, return False
    if s[0] != s[-1]:
        return False
    # 2. Now return whether the middle part
    #    is a palindrome
    return palin(s[1:-1])