Performs the category methods: Retrieve a list of all or part of our category tree. Does this by using the id string provided - should be the id of the category you wish to retrieve.
public Category RetrieveCategoriesById(string id) { var url = Constants.CATEGORIES; if (string.IsNullOrEmpty(id)) { url += Constants.XML; } else { url += String.Format(Constants.Culture, "/{0}{1}", id, Constants.XML); } return RetrieveCategoriesByQueryString(url); }