Return a list of 12 sets. Each sets contains the years included in the POT record period.

        :param pot_dataset: POT dataset (records and meta data)
        :type pot_dataset: :class:`floodestimation.entities.PotDataset`

def _pot_month_counts(self, pot_dataset):
        """
        Return a list of 12 sets. Each sets contains the years included in the POT record period.

        :param pot_dataset: POT dataset (records and meta data)
        :type pot_dataset: :class:`floodestimation.entities.PotDataset`
        """
        periods = pot_dataset.continuous_periods()
        result = [set() for x in range(12)]
        for period in periods:
            year = period.start_date.year
            month = period.start_date.month
            while True:
                # Month by month, add the year
                result[month - 1].add(year)
                # If at end of period, break loop
                if year == period.end_date.year and month == period.end_date.month:
                    break
                # Next month (and year if needed)
                month += 1
                if month == 13:
                    month = 1
                    year += 1
        return result