class Unique:
    def _init__(self):
        self.__class__._counter += 1
        self._id_num = self.__class__._counter # I'm trying to have a counter for each subclass
        self._type_name = self.__class__.__name__

    def __str__(self):
        return '{0} #{1}'.format(self._type_name, self._id_num)

    def log(self, *data):
        print('[{0}]'.format(self), *data)

    @property
    def id_num(self):
        return self._id_num

class Job(Unique):
    def __init__(self):
        super().__init__()

    def run(self):
        self.log('Started')

    def poll(self):
        ''' Returns `None` if the job is still running
            or a (return code, err/info string) pair if it has stopped '''
        return None