code: function(err) {
                  // If we aborted, ignore it
                  if (req.wasAborted) {
                      return;
                  }
  
                  if (err && err.status === 401 && that._shouldAutoLogin()) {
                      // If we had an authorization error, we'll try and login
                      // again, but only once
                      that.sessionKey = null;
                      that.login(function(err, success) {
                          // If we've already aborted the request,
                          // just do nothing
                          if (req.wasAborted) {
                              return;
                          }
  
                          if (err) {
                              // If there was an error logging in, send it through
                              callback(err);
                          }
                          else {
                              // Relogging in was successful, so we execute
                              // our task again.
                              task(callback);
                          }
                      });
                  }
                  else {
                      callback.apply(null, arguments);
                  }
              }
docs: This is the callback that will be invoked if we are currently logged in but our session key expired (i.e. we get a 401 response from the server). We will only retry once.