code: function canResultsBeSummed(item) {
    var result = true;
    if (defined(item.cannotSum)) {
      if (typeof item.cannotSum === "object") {
        var conceptItems = item._concepts[0].items;
        conceptItems.forEach(concept => {
          var valuesThatCannotDisplayPercent = item.cannotSum[concept.id];
          if (defined(valuesThatCannotDisplayPercent)) {
            var activeValueIds = concept.activeItems.map(
              activeConcept => activeConcept.id
            );
            if (
              valuesThatCannotDisplayPercent.some(
                cannotValue => activeValueIds.indexOf(cannotValue) >= 0
              )
            ) {
              result = false;
            }
          }
        });
      } else {
        result = !item.cannotSum; // ie. if it is true or false.
      }
    }
    return result;
  }
docs: Returns true if the results of this can be summed meaningfully. By default, we assume they can be. But if item.cannotSum is set, at least some selections may be rates or averages (rather than counts or totals), which cannot be summed.