docs: function() {
          var i, n = this.numHierarchies,
              hierarchies = {}, member, members = [],
              tuple = {
                  index: this._tupleIndex,
                  hierarchies: hierarchies,
                  members: members
              }
          ;
          for (i=0; i < n; i++) {
            member = this._member(i);
            hierarchies[this._hierarchyOrder[i]] = member;
            members.push(member);
          }
          return tuple;
      }