def meter_data_to_csv(meter_data, path_or_buf):
    """ Write meter data to CSV. See also :any:`pandas.DataFrame.to_csv`.

    Parameters
    ----------
    meter_data : :any:`pandas.DataFrame`
        Meter data DataFrame with ``'value'`` column and
        :any:`pandas.DatetimeIndex`.
    path_or_buf : :any:`str` or file handle, default None
        File path or object, if None is provided the result is returned as a string.
    """
    if meter_data.index.name is None:
        meter_data.index.name = "start"
    return meter_data.to_csv(path_or_buf, index=True)
Write meter data to CSV. See also :any:`pandas.DataFrame.to_csv`.

    Parameters
    ----------
    meter_data : :any:`pandas.DataFrame`
        Meter data DataFrame with ``'value'`` column and
        :any:`pandas.DatetimeIndex`.
    path_or_buf : :any:`str` or file handle, default None
        File path or object, if None is provided the result is returned as a string.