/// <summary>
/// 指定したScreenName(TwitterのID名)のツイートを取得
/// </summary>
/// <param name="screenName">TwitterのID名</param>
/// <returns></returns>
public async Task<ListedResponse<Status>> GetUserTimeline(string screenName)
{
    //ラムダ式の代わりにDictionaryでも渡せます
    var param = new Dictionary<string, object>
    {
        ["count"] = 100,
        ["screen_name"] = screenName,
    };
    return await _tokens.Statuses.UserTimelineAsync(param);
}