public async Task AddToMany(Activity activity, IEnumerable<string> feedIds)
{
var request = _client.BuildAppRequest("feed/add_to_many/", HttpMethod.POST);
request.SetJsonBody(
"{" + string.Format("\"activity\": {0}, \"feeds\": {1}", activity.ToJson(this._client), JsonConvert.SerializeObject(feedIds)) + "}"
);
_client.SignRequest(request);
var response = await _client.MakeRequest(request);
if (response.StatusCode != System.Net.HttpStatusCode.Created)
throw StreamException.FromResponse(response);
}