code: function visibleIp(callback) {
    if (process.env.CP_VISIBLE_IP) {
      return process.nextTick(function() { callback(null, process.env.CP_VISIBLE_IP); });
    }
  
    http.get(proxy('http://cp.vu/show_my_ip'), function(response) {
      var ip = '';
  
      response.on('data', function(chunk) { ip += chunk; });
      response.on('end', function() { callback(null, ip); });
  
    }).on('error', function(error) { callback(error); }).end();
  }
docs: Tries to determine the visible ip address and upon success, asynchronously calls <code>callback</code> passing the ip
  as second argument. If <code>process.env.CP_VISIBLE_IP</code> is set no further detection takes place and callback is
  called in the next tick. Intended mostly for testing purposes.