public async Task DownloadFileAsStringAsync()
{
string skylink = "AAAAQZg5XQJimI9FGR73pOiC2PnflFRh03Z4azabKz6bVw";
var result = await _client.DownloadFileAsStringAsync(skylink);
Assert.AreEqual("this is a test file", result.file);
Assert.AreEqual("text/plain", result.contentType);
Assert.AreEqual("test.txt", result.fileName);
}