'Attempt to automatically handle subscription requests.
Subscriptions will be approved if the request is from
a whitelisted JID, of :attr:`auto_authorize` is True. They
will be rejected if :attr:`auto_authorize` is False. Setting
:attr:`auto_authorize` to ``None`` will disable automatic
subscription handling (except for whitelisted JIDs).
If a subscription is accepted, a request for a mutual
subscription will be sent if :attr:`auto_subscribe` is ``True``.'

def _handle_new_subscription(self, pres):

    roster = self.roster[pres[u'to']]
    item = self.roster[pres[u'to']][pres[u'from']]
    if item[u'whitelisted']:
        item.authorize()
        if roster.auto_subscribe:
            item.subscribe()
    elif roster.auto_authorize:
        item.authorize()
        if roster.auto_subscribe:
            item.subscribe()
    elif (roster.auto_authorize == False):
        item.unauthorize()
