'Increment the counter (overflow rolls back to 0).'

def increment(self):

    for i in xrange((len(self._counter) - 1), (-1), (-1)):
        self._counter[i] += 1
        if (self._counter[i] < 256):
            break
        self._counter[i] = 0
    else:
        self._counter = ([0] * len(self._counter))
