code: function _findUnmergedRange(tableData, $start, $end) {
    const cellIndexData = tableDataHandler.createCellIndexData(tableData);
    const startCellIndex = tableDataHandler.findCellIndex(cellIndexData, $start);
    const endCellIndex = tableDataHandler.findCellIndex(cellIndexData, $end);
    let startRowIndex, endRowIndex, startColIndex, endColIndex;
  
    if (startCellIndex.rowIndex > endCellIndex.rowIndex) {
      startRowIndex = endCellIndex.rowIndex;
      endRowIndex = startCellIndex.rowIndex;
    } else {
      startRowIndex = startCellIndex.rowIndex;
      endRowIndex = endCellIndex.rowIndex;
    }
  
    if (startCellIndex.colIndex > endCellIndex.colIndex) {
      startColIndex = endCellIndex.colIndex;
      endColIndex = startCellIndex.colIndex;
    } else {
      startColIndex = startCellIndex.colIndex;
      endColIndex = endCellIndex.colIndex;
    }
  
    return {
      start: {
        rowIndex: startRowIndex,
        colIndex: startColIndex
      },
      end: {
        rowIndex: endRowIndex,
        colIndex: endColIndex
      }
    };
  }
docs: Find unmerged table range.
  @param {Array.<Array.<object>>} tableData - table data
  @param {jQuery} $start - start talbe cell jQuery element
  @param {jQuery} $end - end table cell jQuery element
  @returns {{
  start: {rowIndex: number, colIndex: number},
  end: {rowIndex: number, colIndex: number}
  }}
  @private