Determine the current usage for each limit of this service,
        and update corresponding Limit via
        :py:meth:`~.AwsLimit._add_current_usage`.

def find_usage(self):
        """
        Determine the current usage for each limit of this service,
        and update corresponding Limit via
        :py:meth:`~.AwsLimit._add_current_usage`.
        """
        logger.debug("Checking usage for service %s", self.service_name)
        for lim in self.limits.values():
            lim._reset_usage()
        elb_usage = self._find_usage_elbv1()
        alb_usage = self._find_usage_elbv2()
        logger.debug('ELBs in use: %d, ALBs in use: %d', elb_usage, alb_usage)
        self.limits['Active load balancers']._add_current_usage(
            (elb_usage + alb_usage),
            aws_type='AWS::ElasticLoadBalancing::LoadBalancer',
        )
        self._have_usage = True
        logger.debug("Done checking usage.")