Is the given 'threads' iterator pointing at a valid thread.
When this function returns TRUE, notmuch_threads_get will return a
valid object. Whereas when this function returns FALSE,
notmuch_threads_get will return NULL.
If passed a NULL pointer, this function returns FALSE
See the documentation of notmuch_query_search_threads for example
code showing how to iterate over a notmuch_threads_t object.
Is the given 'threads' iterator pointing at a valid thread.
When this function returns TRUE, notmuch_threads_get will return a valid object. Whereas when this function returns FALSE, notmuch_threads_get will return NULL.
If passed a NULL pointer, this function returns FALSE
See the documentation of notmuch_query_search_threads for example code showing how to iterate over a notmuch_threads_t object.