code: def tokenize_timeperiod(timeperiod):
      
      assert len(timeperiod) == 10, 'timeperiod {0} does not match accepted format YYYYMMDDHH'.format(timeperiod)
      return timeperiod[:4], timeperiod[4: 6], timeperiod[6: 8], timeperiod[8:],
docs: method breaks given timeperiod into 4 parts: (year, month, day, hour)
      for instance: daily   2015031400 -> ('2013', '03', '14', '00')
                    hourly  2015031413 -> ('2013', '03', '14', '13')
                    monthly 2015030000 -> ('2013', '03', '00', '00')
                    yearly  2015000000 -> ('2015', '00', '00', '00')
      :return: tuple of four values