docs: function addStepToBlock(that, block, stepId, stageId, positions) {
          var stepInBlock;
          // Add step, if not already added.
          if (block.hasItem(stepId)) return false;
  
          stepInBlock = {
              type: stageId,
              item: stepId,
              id: stepId
          };
  
          if (isDefaultStep(that.steps[stepId])) {
              makeDefaultStep(stepInBlock);
          }
          block.add(stepInBlock, positions);
          return true;
      }