Is the given 'tags' iterator pointing at a valid tag.
When this function returns TRUE, notmuch_tags_get will return a
valid string. Whereas when this function returns FALSE,
notmuch_tags_get will return NULL.
See the documentation of notmuch_message_get_tags for example code
showing how to iterate over a notmuch_tags_t object.
Is the given 'tags' iterator pointing at a valid tag.
When this function returns TRUE, notmuch_tags_get will return a valid string. Whereas when this function returns FALSE, notmuch_tags_get will return NULL.
See the documentation of notmuch_message_get_tags for example code showing how to iterate over a notmuch_tags_t object.