public async static Task<UserStatus> ChangeFriendship(this IUserSession session, string screenName = "",
int user_id = 0, bool device=false, bool retweets=false)
{
var parameters = new TwitterParametersCollection();
parameters.Create(screen_name: screenName, user_id: user_id,device:device,retweets:retweets);
if (parameters.EnsureEitherOr("screen_name", "user_id").IsFalse())
{
return session.MapParameterError<UserStatus>(
"Either screen_name or user_id required");
}
return await session.PostAsync(TwitterApi.Resolve("/1.1/friendships/update.json"), parameters)
.ContinueWith(c => c.MapToSingle<UserStatus>());
}