How to get top-most group ID

Figured it out. Code below if anyone else runs into this:

var groupParentId = group.ParentGroupId;
var parentGroup  = null;
while(groupParentId != -1 && groupParentId != 1){
    parentGroup = core_v2_group.Get({Id: groupParentId});
    groupParentId = parentGroup.ParentGroupId;
    if(parentGroup.Id == 227){
        matchingId = true;
    }
}

Figured it out. Code below if anyone else runs into this:

var groupParentId = group.ParentGroupId;
var parentGroup  = null;
while(groupParentId != -1 && groupParentId != 1){
    parentGroup = core_v2_group.Get({Id: groupParentId});
    groupParentId = parentGroup.ParentGroupId;
    if(parentGroup.Id == 227){
        matchingId = true;
    }
}

The top level grouip is always the root group.  $core_v2_group.Root.Id
core_v2_group Script API