code: function(step, next) {
        var currentStep;
        step.steps = copyArray(step.steps);
        currentStep = -1;
        step.next = function() {
          var args;
          currentStep++;
          args = [step].concat(copyArray(arguments));
          if (currentStep >= step.steps.length) {
            return step.callback.apply(null, args);
          } else {
            return step.steps[currentStep].apply(null, args);
          }
        };
        return next();
      }
docs: /*{"name":"ctrl.builders.next", "priority":5}
  This builder adds the `next()` function to the step parameter.
  It should normally be first in the list of builders.