'Append an item to the XLS data
@param rows: the XLS rows array to append to
@param item: the item dict
@param level: the grouping level'

def xls_item_data(self, rows, item, level=0):

    columns = self.data['c']
    cells = {}
    for column in columns:
        cells[column] = item.get(column)
    rows.append(cells)
