Okey I think I found the anwser like this:

go

    resp, err := c.LookupResources(context.Background(), &pb.LookupResourcesRequest{
        ResourceObjectType: "tdesk/group",
        Permission:         "member",
        Subject: &pb.SubjectReference{
            Object: &pb.ObjectReference{
                ObjectType: "tdesk/user",
                ObjectId:   "vural",
            },
        },
    })

    if err != nil {
        log.Fatalf("failed to LookupResources: %s", err)
    }

    for {
        lookupResp, err := resp.Recv()
        if err != nil {
            log.Fatalf("failed to lookup: %s", err)
        }
        log.Println(lookupResp.String())
    }