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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def export_to_xlsx(table, filename_or_fobj=None, sheet_name="Sheet1", *args, **kwargs):
 """Export the rows.Table to XLSX file and return the saved file."""


    workbook = Workbook()
    sheet = workbook.active
    sheet.title = sheet_name
    prepared_table = prepare_to_export(table, *args, **kwargs)

    # Write header
    field_names = next(prepared_table)
    for col_index, field_name in enumerate(field_names):
        cell = sheet.cell(row=1, column=col_index + 1)
        cell.value = field_name

    # Write sheet rows
    _convert_row = _python_to_cell(list(map(table.fields.get, field_names)))
    for row_index, row in enumerate(prepared_table, start=1):
        for col_index, (value, number_format) in enumerate(_convert_row(row)):
            cell = sheet.cell(row=row_index + 1, column=col_index + 1)
            cell.value = value
            if number_format is not None:
                cell.number_format = number_format

    return_result = False
    if filename_or_fobj is None:
        filename_or_fobj = BytesIO()
        return_result = True

    source = Source.from_file(filename_or_fobj, mode="wb", plugin_name="xlsx")
    workbook.save(source.fobj)
    source.fobj.flush()

    if return_result:
        source.fobj.seek(0)
        result = source.fobj.read()
    else:
        result = source.fobj

    if source.should_close:
        source.fobj.close()

    return result