code: def _find_usage_elbv1(self):
          
          logger.debug("Checking usage for ELBv1")
          self.connect()
          lbs = paginate_dict(
              self.conn.describe_load_balancers,
              alc_marker_path=['NextMarker'],
              alc_data_path=['LoadBalancerDescriptions'],
              alc_marker_param='Marker'
          )
          for lb in lbs['LoadBalancerDescriptions']:
              self.limits['Listeners per load balancer']._add_current_usage(
                  len(lb['ListenerDescriptions']),
                  aws_type='AWS::ElasticLoadBalancing::LoadBalancer',
                  resource_id=lb['LoadBalancerName'],
              )
              self.limits[
                  'Registered instances per load balancer'
              ]._add_current_usage(
                  len(lb['Instances']),
                  aws_type='AWS::ElasticLoadBalancing::LoadBalancer',
                  resource_id=lb['LoadBalancerName']
              )
          logger.debug('Done with ELBv1 usage')
          return len(lbs['LoadBalancerDescriptions'])
docs: Find usage for ELBv1 / Classic ELB and update the appropriate limits.
  
          :returns: number of Classic ELBs in use
          :rtype: int