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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 dataset_format_to_extension(ds_format):
 """ Get the preferred Dataset format extension :param str ds_format: Format of the Dataset (expected to be one of `csv` or `xml`) :rtype: str """

    try:
        return DATASET_FORMATS[ds_format]
    except KeyError:
        raise ValueError(
            "dataset_format is expected to be one of %s. '%s' is not valid"
            % (", ".join(DATASET_FORMATS.keys()), ds_format)
        )