lib/oauth2client.js
function (response, body) {
          var tokenResponse;
          try {
             tokenResponse = self._handlePollingResponse(body);
          } catch (e) {
             self._log.error('Error validating get token response', e, true);
             callback(null, e);
             return;
          }
        
          callback(null, tokenResponse);
       }
function (response, body) {
          var tokenResponse;
          try {
             tokenResponse = self._handlePollingResponse(body);
          } catch (e) {
             self._log.error('Error validating get token response', e, true);
             callback(null, e);
             return;
          }
        
          callback(null, tokenResponse);
       }
function ( response , body ) { var tokenResponse ; try { tokenResponse = self . _handlePollingResponse ( body ) ; } catch ( e ) { self . _log . error ( 'Error validating get token response' , e , true ) ; callback ( null , e ) ; return ; } callback ( null , tokenResponse ) ; }
success response callback
success response callback