Determines the baseline number (i.e. version) of ESA .SAFE product

        :return: baseline number
        :rtype: str
        :raises: ValueError

def get_baseline(self):
        """ Determines the baseline number (i.e. version) of ESA .SAFE product

        :return: baseline number
        :rtype: str
        :raises: ValueError
        """
        if self.safe_type is EsaSafeType.COMPACT_TYPE:
            baseline = self.product_id.split('_')[3].lstrip('N')
            if len(baseline) != 4:
                raise ValueError('Unable to recognize baseline number from the product id {}'.format(self.product_id))
            return '{}.{}'.format(baseline[:2], baseline[2:])
        return self._read_baseline_from_info()