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

def tokenize_timeperiod(timeperiod):
    """
    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
    """
    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:],