learning async promises

gistfile1.txt

var rsApiClient = function (){
   var self = this;

   self.login = function (host, refreshToken){
     var fetch = require('node-fetch');
     var FormData = require('form-data');
     var form = new FormData();

     form.append('refresh_token', refreshToken);
     form.append('grant_type', 'refresh_token');

     var result = fetch('https://'+host+'/api/oauth2', {
       headers: { 'X-API-Version': '1.5' },
       method: 'POST',
       body: form
     }).then(function(res) {
       return res.text()
     })
     return result
   };
};

module.exports = rsApiClient;