parse(xhr.responseText));
                }
            }
        };
        var get = function(uri, cb) {
            var xhr = new XMLHttpRequest();
            xhr.open('GET', uri, true);
            xhr.setRequestHeader('Content-Type', 'application/json;charset=UTF-8');
            xhr.send();
            xhr.onreadystatechange = function() {
                if (xhr.readyState === 4) {
                    cb(xhr.status === 200);
                }
            }
        };
        function subscribe() {
 