docs: function getChoiceTable(that, i) {
          var ct, s, idx;
          idx = that.order[i];
          s = mixinSettings(that, that.itemsSettings[idx], i);
          ct = node.widgets.get('ChoiceTable', s);
          if (that.itemsById[ct.id]) {
              throw new Error('ChoiceTableGroup.buildTable: an item ' +
                              'with the same id already exists: ' + ct.id);
          }
          if (!ct.leftCell) {
              throw new Error('ChoiceTableGroup.buildTable: item ' +
                              'is missing a left cell: ' + s.id);
          }
          that.itemsById[ct.id] = ct;
          that.items[idx] = ct;
          that.itemsMap[ct.id] = idx;
          return ct;
      }