* the given iterator for each of them.
*
* @param cls our "struct Plugin*"
+ * @param offset offset of the result (modulo num-results);
+ * specific ordering does not matter for the offset
* @param type entries of which type should be considered?
* Use 0 for any type.
* @param proc function to call on the matching value;
* iterator.
*
* @param cls closure
- * @param next_cls closure to pass to the "next" function.
* @param key key for the content
* @param size number of bytes in data
* @param data content stored