def get_dataset_date(self, date_format=None):
        # type: (Optional[str]) -> Optional[str]
        """Get dataset date as string in specified format. For range returns start date.
        If no format is supplied, an ISO 8601 string is returned.

        Args:
            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
        """
        dataset_date = self.get_dataset_date_as_datetime()
        return self._get_formatted_date(dataset_date, date_format)
Get dataset date as string in specified format. For range returns start date.
        If no format is supplied, an ISO 8601 string is returned.

        Args:
            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