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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 _get_formatted_date(dataset_date, date_format=None):
 # type: (Optional[datetime], Optional[str]) -> Optional[str] """Get supplied dataset date as string in specified format. If no format is supplied, an ISO 8601 string is returned. Args: dataset_date (Optional[datetime.datetime]):
 dataset date in datetime.datetime format date_format (Optional[str]):
 Date format. None is taken to be ISO 8601. Defaults to None. Returns: Optional[str]: Dataset date string or None if no date is set """

        if dataset_date:
            if date_format:
                return dataset_date.strftime(date_format)
            else:
                return dataset_date.date().isoformat()
        else:
            return None