public string addForum(string forumName, string requestingUser) { List <string> input = new List <string>() { forumName, requestingUser }; if (Constants.isValidInput(input)) { lock (o) { string res = _um.addForum(forumName, requestingUser); if (res.Equals(Constants.SUCCESS)) { return(_fm.addForum(forumName)); } return(res); } } return(Constants.INVALID_INPUT); }