var promise = require('bluebird');


function download(url) {
    return Promise.resolve()
}

function untar(tarfile) {
    return Promise.resolve()
}

function install(files) {
    return Promise.resolve(files)
}

function update() {
    return Promise.resolve(files)
}

function getTar(url) {
    if (needDownload) {
        return download(url);
    }
    return Promise.resolve(url);
}

function onError(err) {
    console.log("Error");
}

getTar(url).then(untar).then(install).then(update, onError);