Check if (and which) avatar is sitting on a specific object

key f(key kOBJECTKEY)
{
     list lAvatars = llGetAgentList(AGENT_LIST_REGION, []);
        integer iCount;
        for (iCount = 0; iCount < llGetListLength(lAvatars); iCount++)
        {
            if (llList2Key(llGetObjectDetails(llList2Key(lAvatars, iCount), [OBJECT_ROOT]),0) == kOBJECTKEY)
            {
                return llList2Key(lAvatars, iCount);
            }
        }
        return NULL_KEY;
}
default
{

    touch_start(integer total_number)
    {
        key k = f(llGetKey());
        if (k != NULL_KEY)
        {
            llSay(0, (string)k + " is sitting on me!");
        }
        else
        {
            llSay(0, "Nobody is sitting!");
        }
    }
}