docs: function executeShifts(node) {
      var children = node.children;
      var n = children.length;
      var shift = 0;
      var change = 0;
      while (--n >= 0) {
          var child = children[n];
          child.hierNode.prelim += shift;
          child.hierNode.modifier += shift;
          change += child.hierNode.change;
          shift += child.hierNode.shift + change;
      }
  }