code: def _find_usage_security_groups(self):
          
          num_groups = 0
          # If EC2-Classic isn't available (e.g., a new account)
          # this method will fail with:
          #   Code:    "InvalidParameterValue"
          #   Message: "Use of cache security groups is not permitted in
          #             this API version for your account."
          #   Type:    "Sender"
          try:
              paginator = self.conn.get_paginator(
                  'describe_cache_security_groups')
              for page in paginator.paginate():
                  for secgroup in page['CacheSecurityGroups']:
                      num_groups += 1
          except ClientError as ex:
              if ex.response['Error']['Code'] != 'InvalidParameterValue':
                  raise ex
              logger.debug("caught ClientError checking ElastiCache security "
                           "groups (account without EC2-Classic?)")
  
          self.limits['Security Groups']._add_current_usage(
              num_groups,
              aws_type='WS::ElastiCache::SecurityGroup'
          )
docs: find usage for elasticache security groups