code: function applyProxy(options, cb) {
    npmconf.load({}, function (er, conf) {
      var proxyUrl;
  
      if (!er) {
        proxyUrl = conf.get('https-proxy') ||
                   conf.get('proxy') ||
                   conf.get('http-proxy');
      }
  
      var env = process.env;
  
      options.proxy = proxyUrl ||
                      env.HTTPS_PROXY ||
                      env.https_proxy ||
                      env.HTTP_PROXY ||
                      env.http_proxy;
  
      cb(options);
    });
  }
docs: Get applyProxy settings
  
  @param {Object} options
  @param {Function} cb
  @api private