Follow user using TweetSharp

I use following code to follow user:

TwitterService ts = new TwitterService(TWI_CONSUMER_KEY, TWI_CONSUMER_SECRET);
ts.AuthenticateWith(token.Token, token.Secret);

var users = ts.SearchForUser(query); //Get list o开发者_运维技巧f users by query
//...
foreach (var user in users) 
{
    var u = ts.FollowUser(user.Id); //Follow user
}

and get exception:

System.ArgumentException: Item with the same key has already been added

Are there any mistakes? Please help me.

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The exception is being thrown as the user your adding, you're already following. You'll need to either:

1. Check if your already following that user, then follow
2. Wrap the var u.ts.FollowerUser(..) in a try/catch so the loop will continue