bool bson_iter_find (bson_iter_t *iter, const char *key);
The bson_iter_find()function shall advance iterto the element named keyor exhaust all elements of iter. If iteris exhausted, false is returned and itershould be considered invalid.
key is case-sensitive. For a case-folded version, see bson_iter_find_case().
true is returned if the requested key was found. If not, iterwas exhausted and should now be considered invalid.