toggleOption = function(shouldCollapse) {
      var ms = 0;
      for (var i = 0; i < topBlocks.length; i++) {
        var block = topBlocks[i];
        while (block) {
          setTimeout(block.setCollapsed.bind(block, shouldCollapse), ms);
          block = block.getNextBlock();
          ms += DELAY;
        }
      }
    }
Option to collapse or expand top blocks.
@param {boolean} shouldCollapse Whether a block should collapse.
@private