code: function buildQueryString (obj) {
    var query = Object.keys(obj).reduce(function (acc, key) {
      return acc + '&' + querystring.escape(key) + '=' +
        querystring.escape(obj[key])
    }, '')
    return query.replace(/^&/, '?')
  }
docs: Flattens the key / value pairs in the supplied object into a query string
  for use in an HTTP request.
  @param {Object} obj - Object containing the key/value pairs to convert into
  a query string.
  @returns {String} The query string.
  @private