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