OpenTween.MyLists.AddToList C# (CSharp) Method

        private async Task AddToList(ListElement list)
        {
            try
            {
                await this.twitterApi.ListsMembersCreate(list.Id, this.contextScreenName);

                var index = this.ListsCheckedListBox.Items.IndexOf(list);
                this.ListsCheckedListBox.SetItemCheckState(index, CheckState.Checked);
            }
            catch (WebApiException ex)
            {
                MessageBox.Show(string.Format(Properties.Resources.ListManageOKButton2, ex.Message));
            }
        }