Application.Services.factory('tags', ["mcapi",
    function tags(mcapi) {
        var service = {
            tags: [],

            createTag: function (tag, item_id) {
                mcapi('/tags/item/%', item_id)
                    .success(function (tag) {
                        return tag;
                    }).post(tag);
            },

            removeTag: function (tag_id, item_id) {
                mcapi('/tags/%/item/%', tag_id, item_id)
                    .success(function (tag) {
                        return tag;
                    }).delete();
            }
        };
        return service;
    }]);

Application.Services.factory('tags', ["mcapi",
    function tags(mcapi) {
        return {
            tags: [],

            createTag: function (tag, item_id) {
                mcapi('/tags/item/%', item_id)
                    .success(function (tag) {
                        return tag;
                    }).post(tag);
            },

            removeTag: function (tag_id, item_id) {
                mcapi('/tags/%/item/%', tag_id, item_id)
                    .success(function (tag) {
                        return tag;
                    }).delete();
            }
        };
    }]);

Remove variable declaration for service and just return the object.
Remove variable declaration for service and just return the object.
