Никита Каменев

$('#blackstyle').click(function (){
    $('link[href="style1.css"]').attr('href', 'style2.css');
});
$('#original').click(function (){
    $('link[href="style2.css"]').attr('href', 'style1.css');
});

def presence(conn, event):
    if event.getType() == 'subscribe':
        client.send(xmpp.Presence(to=event.getFrom(), typ='subscribed'))

client.RegisterHandler('presence', presence)