title: IBM Push : cannot use sendNotificationByDeviceIds in ibmpush.js
body: <p>i have a application and use the function sendNotificationByDeviceIds  as below:</p>
  
  <pre><code>PushNotificationToConsumer: function(req, res) {
  
          queryCustomer.find({jpay_no : jpay_no}).done(function(customerReturn){
              if(customerReturn.length &gt; 0){
                  var device_id = customerReturn[0].attributes.device_id.toString();
                  req.ibmpush.sendNotificationByDeviceIds(message, [device_id], null).then(function(response){
                      res.json({success : true, message : 'Send notification to patient with device_id:' +device_id+ ' successful ' });
                  },function(err){                      
                      res.json(err);
                  });
              }else{
  
              }
          }, function(err){
              res.json(err);
          })
  
      }
  </code></pre>
  
  <p>The error message: 
  <a href="https://i.stack.imgur.com/oYVKB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oYVKB.png" alt="enter image description here"></a></p>
  
  <p>on app.js: I declared ibmpush = require('ibmpush')</p>
  
  <p>please help to give me your thoughts.
  Thanks</p>