code: func OptionLoadBalancer(nid string) SandboxOption {
  	return func(sb *sandbox) {
  		sb.loadBalancerNID = nid
  		sb.oslTypes = append(sb.oslTypes, osl.SandboxTypeLoadBalancer)
  	}
  }
docs: // OptionLoadBalancer function returns an option setter for marking a
  // sandbox as a load balancer sandbox.