Increments the counter by the given amount
        :param amount: the amount to increment by (default 1)
        :return:       the incremented value of the counter

def increment(self, amount=1):
        """Increments the counter by the given amount
        :param amount: the amount to increment by (default 1)
        :return:       the incremented value of the counter
        """
        self.__lock.acquire()
        self.__count += amount
        v = self.value()
        self.__lock.release()
        return v