The new feature allows to use ES6 generators syntax when defining modules and requiring them:

define(function* () {
  var _ = yield require('../vendor/lodash');
  return {
    //...
  };
});

But it still needs more discussion and real world feedbacks. I opened this issue to discuss all the possible feedbacks around it. Feel free to bring up your views regarding the way ES6 generators are being used in the code block above.