If 'messages' is already pointing at the last message then the
iterator will be moved to a point just beyond that last message,
(where notmuch_messages_valid will return FALSE and
notmuch_messages_get will return NULL).
See the documentation of notmuch_query_search_messages for example
code showing how to iterate over a notmuch_messages_t object.
Move the 'messages' iterator to the next message.
If 'messages' is already pointing at the last message then the iterator will be moved to a point just beyond that last message, (where notmuch_messages_valid will return FALSE and notmuch_messages_get will return NULL).
See the documentation of notmuch_query_search_messages for example code showing how to iterate over a notmuch_messages_t object.