code: function () {
                  try {
                      authHandler.sign(authInterface, context.item.request, function (err) {
                          // handle all types of errors in one place, see catch block
                          if (err) { throw err; }
  
                          done();
                      });
                  }
                  catch (err) {
                      // handles synchronous and asynchronous errors in auth.sign
                      run.triggers.console(context.coords,
                          'warn',
                          'runtime~' + authType + '.auth: could not sign the request: ' + (err.message || err),
                          err
                      );
  
                      // swallow the error, we've warned the user
                      done();
                  }
              }
docs: get auth handler