docs: function(hierarchyIndexOrName){
          if (_isUnd(hierarchyIndexOrName)) {
            index = this._hierarchyIndex;
          }
          var index, hierarchyName;
          switch(typeof(hierarchyIndexOrName)){
              case "string":
                  index = this.hierarchyIndex(hierarchyIndexOrName);
                  hierarchyName = hierarchyIndexOrName;
                  break;
              case "number":
                  if (hierarchyIndexOrName !== parseInt(hierarchyIndexOrName, 10) ||
                      hierarchyIndexOrName >= this.numHierarchies
                  )
                      Xmla.Exception._newError(
                          "INVALID_HIERARCHY",
                          "Xmla.Dataset.Axis.hierarchyDef",
                          hierarchyIndexOrName
                      )._throw();
                  index = hierarchyIndexOrName;
                  break;
          }
          return this._member(index);
      }