docs: function () {
      "use strict";
  
      return new Promise(function (resolve, reject) {
        var numberOfRetries = 5;
  
        (function retry () {
          var port = 4000 + Math.floor(Math.random() * 1000);
          portscanner.checkPortStatus(port, 'localhost', function (err, status) {
            if (err || status !== 'closed') {
              if (--numberOfRetries > 0) {
                setTimeout(retry);
              } else {
                reject('Cannot find a free port... giving up');
              }
            } else {
              resolve(port);
            }
          });
        })();
      });
    }