Is any permutation of a string a palindrome?

palin.py

#!/usr/bin/env python

import sys

def is_odd(x):
    return x % 2 == 1

# is any permutation of a string a palindrome?
def anypalin(string):
    charcounts = {}
    for ch in string:
        if ch in charcounts:
            charcounts[ch] += 1
        else:
            charcounts[ch] = 1
    odds = 0
    for (k,v) in charcounts.iteritems():
        if is_odd(v):
            odds += 1
            if odds > 1:
                return False
    return odds < 2

def test():
    cases = {
        "civic": True,
        "cciiv": True,
        "civil": False,
        "ciivl": False
    }

    for (k,v) in cases.iteritems():
        if anypalin(k) != v:
            print "Failed: expected %s to be %s" % (k,v)
            sys.exit(1)
    print "all tests passed"

if __name__ == "__main__":
    test()