code: function addBlock(that, id, type, positions, type2) {
          var block, options;
          options = {};
  
          options.id = id || J.uniqueKey(that.blocksIds, type);
          options.type = type;
          options.positions = positions;
  
          that.currentBlockType = type2;
  
          // Create the new block, and add it block arrays.
          block = new node.Block(options);
          that.unfinishedBlocks.push(block);
          that.blocks.push(block);
  
          // Save block id into the blocks map.
          that.blocksIds[options.id] = (that.blocks.length - 1);
      }
docs: #### addBlock
  
  Adds a new block of the specified type to the sequence
  
  @param {Stager} that The stager instance
  @param {string} id Optional. The id of the stage block
  @param {string} type The block type
  @param {string|number} positions The allowed positions for the block
  @param {string} type2 The value that the currentBlock variable
  will be set to (BLOCK_STAGE or BLOCK_STEP)