code: function getSortValue(column, rowData, rowNumber, tableData, columns) {
    var cellData = getCellData(column, rowData, rowNumber, tableData, columns);
  
    return getSortValueFromCellData(cellData, column, rowData);
  }
docs: Gets the sort value for a cell by first computing the cell data. If
  no sortValue function is provided on the column, the cellData is
  returned.
  
  @param {Object} column The column definition
  @param {Object} rowData The data for the row
  @param {Number} rowNumber The number of the row
  @param {Object[]} tableData The array of data for the whole table
  @param {Object[]} columns The column definitions for the whole table
  @return {Any} The sort value for this cell