public async Task Clean()
        {
            if (this.spark == null)
            {
                return;
            }

            var r = await spark.ListSpacesAsync(sortBy : SpaceSortBy.Created, max : 50);

            while (true)
            {
                if (r.IsSuccessStatus && r.Data.HasItems)
                {
                    foreach (var item in r.Data.Items)
                    {
                        if (item.Title.Contains(UNIT_TEST_CREATED_PREFIX))
                        {
                            await spark.DeleteSpaceAsync(item);
                        }
                    }
                }

                if (unitTestSpace == null && r.HasNext)
                {
                    r = await r.ListNextAsync();
                }
                else
                {
                    break;
                }
            }
        }