code: function _getHeaderAligns(tableData) {
    const [headRowData] = tableData;
  
    return headRowData.map(cellData => {
      let align;
  
      if (util.isExisty(cellData.colMergeWith)) {
        ({align} = headRowData[cellData.colMergeWith]);
      } else {
        ({align} = cellData);
      }
  
      return align;
    });
  }
docs: Get header aligns.
  @param {Array.<Array.<object>>} tableData - table data
  @returns {Array.<?string>}
  @private