docs: def condense(self):
          """
          Condense the data set to the distinct intervals based on the pseudo key.
          """
          for pseudo_key, rows in self._rows.items():
              tmp1 = []
              intervals = sorted(self._derive_distinct_intervals(rows))
              for interval in intervals:
                  tmp2 = dict(zip(self._pseudo_key, pseudo_key))
                  tmp2[self._key_start_date] = interval[0]
                  tmp2[self._key_end_date] = interval[1]
                  tmp1.append(tmp2)
  
              self._rows[pseudo_key] = tmp1