docs: def increment(self):
          '''Increment the counter (overflow rolls back to 0).'''
  
          for i in xrange(len(self._counter) - 1, -1, -1):
              self._counter[i] += 1
  
              if self._counter[i] < 256: break
  
              # Carry the one
              self._counter[i] = 0
  
          # Overflow
          else:
              self._counter = [ 0 ] * len(self._counter)