Retrieve object_ids of valid taxonomy and term.
The strings of $taxonomies must exist before this function will continue. On failure of finding a valid taxonomy, it will return an WP_Error class, kind of like Exceptions in PHP 5, except you can’t catch them. Even so, you can still test for the WP_Error class and get the error message.
The $terms aren’t checked the same as $taxonomies, but still need to exist for $object_ids to be returned.
It is possible to change the order that object_ids is returned by either using PHP sort family functions or using the database by using $args with either ASC or DESC array. The value should be in the key named ‘order’.
(int|array) (Required) Term id or array of term ids of terms that will be used.
(string|array) (Required) String of taxonomy name or Array of string values of taxonomy names.
(array|string) (Optional) Change the order of the object_ids, either ASC or DESC.
Default value: array()
(WP_Error|array) If the taxonomy does not exist, then WP_Error will be returned. On success. the array can be empty meaning that there are no $object_ids found or it will return the $object_ids found.