* notmuch_threads_t object. (For consistency, we do provide a
* notmuch_threads_destroy function, but there's no good reason
* to call it if the query is about to be destroyed).
+ *
+ * If a Xapian exception occurs this function will return NULL.
*/
notmuch_threads_t *
notmuch_query_search_threads (notmuch_query_t *query);