code: function(index){
          if (_isUnd(index)) index = this._hierarchyIndex;
          if (index !== parseInt(index, 10) ||
              index >= this.numHierarchies
          )
              Xmla.Exception._newError(
                  "INVALID_HIERARCHY",
                  "Xmla.Dataset.Axis.hierarchyDef",
                  index
              )._throw();
          return this._hierarchyOrder[index];
      }
docs: Gets the name of the hierarchy identified by the specified index, or the name of the current hierarchy (in case the index argument is omitted).
  @method hierarchyName
  @param hierarchyIndex {int} The ordinal of the hierarchy for which the name is to be retrieved. When omitted, the name of the current hierarchy is returned.
  @return {string} The name of the hierarchy specified by the argument index, or the name of the current hierarchy if the index argument is omitted.