// this code is called in a tight loop
      var colKey = [];
      var rowKey = [];
      var _iteratorNormalCompletion3 = true;
      var _didIteratorError3 = false;
      var _iteratorError3 = undefined;

      try {
        for (var _iterator3 = Array.from(this.props.cols)[Symbol.iterator](), _step3; !(_iteratorNormalCompletion3 = (_step3 = _iterator3.next()).done); _iteratorNormalCompletion3 = true) {
          var x = _step3.value;

          colKey.push(x in record ? record[x] : 'null');
        }
      } catch (err) {
        _didIteratorError3 = true;
        _iteratorError3 = err;
      } finally {
        try {
          if (!_iteratorNormalCompletion3 && _iterator3.return) {
            _iterator3.return();
          }
        } finally {
          if (_didIteratorError3) {
            throw _iteratorError3;
          }
        }
      }

      var _iteratorNormalCompletion4 = true;
      var _didIteratorError4 = false;
      var _iteratorError4 = undefined;

      try {
        for (var _iterator4 = Array.from(this.props.rows)[Symbol.iterator](), _step4; !(_iteratorNormalCompletion4 = (_step4 = _iterator4.next()).done); _iteratorNormalCompletion4 = true) {
          var _x16 = _step4.value;

          rowKey.push(_x16 in record ? record[_x16] : 'null');
        }
      } catch (err) {
        _didIteratorError4 = true;
        _iteratorError4 = err;
      } finally {
        try {
          if (!_iteratorNormalCompletion4 && _iterator4.return) {
            _iterator4.return();
          }
        } finally {
          if (_didIteratorError4) {
            throw _iteratorError4;
          }
        }
      }

// this code is called in a tight loop
    const colKey = [];
    const rowKey = [];
    for (const x of Array.from(this.props.cols)) {
      colKey.push(x in record ? record[x] : 'null');
    }
    for (const x of Array.from(this.props.rows)) {
      rowKey.push(x in record ? record[x] : 'null');
    }