def add_data_export_arg(parser):
    """
    Add export argument.

    Export argument configures data export to a text file in table format.

    Is defined by ``-x`` and ``--export``.

    Parameters
    ----------
    parser : `argparse.ArgumentParser <https://docs.python.org/3/library/argparse.html#argparse.ArgumentParser>`_
        The argument parser to which add the export argument.
    """
    parser.add_argument('-x', '--export', help=
        "Export calculated values to a CSV file. Defaults to 'results.csv', alternatively, you can give a specific file name."
        , default=False, const='results.csv', nargs='?')
