code: function(node) {
      var hasAggregators = node instanceof lf.proc.ProjectStep &&
          node.hasAggregators();
      return hasAggregators ||
          node instanceof lf.proc.OrderByStep ||
          node.getChildCount() != 1 ||
          node instanceof lf.proc.SelectStep;
    }
docs: /*
  LIMIT and SKIP needs to be executed after
  - projections that include either groupBy or aggregators,
  - joins/cross-products,
  - selections,
  - sorting
  have been calculated. Therefore if such nodes exist this optimization can
  not be applied.