OG Subgroups - call function _og_subgroups_get_inherited_users I am trying to create a custom rule for OG Subgroups to email the members of a subgroup when content is added to it.

In og_subgroups.common.inc I can see the function I wish to use to return the inherited users of a subgroup 

function _og_subgroups_get_inherited_users($group_type, $group_id, $states = array(OG_STATE_ACTIVE))


In my custom rule action I'm not sure what I should be passing to the function as $group_type and $group_id parameters. I have tried things like "node" and the NID of the group:

$array = _og_subgroups_get_inherited_users("node", 27);


Once I get it working with a hardcoded node e.g. node 27 I will then try to pass the details of the parent groupd that content has been added to.

I'm using OG Subgroups ﻿﻿7.x-2.0-beta1. For the full background into why I'm creating this custom rule action you can see my original drupal answers question
I was able to solve this by creating a custom og_subgroups.rules.inc file. For details of this see my answer in: Email all Organic Group members when a subgroup is created 

The line in question above needed to be:

$inherited_users = _og_subgroups_get_inherited_users("node", $nid);