I would like to create a list of dates, which summarize the first three hours and then the next three. Something like:
`['2016/05/01-00-02h', '2016/05/01-03-05h', '2016/05/01-06-08h',.....'2016/05/31-21-23h']`. Until now, I have only a list of dates without the summary. 

```
from datetime import datetime as dt, timedelta

deb = '20160501'
fin = '20160531'

start = dt.strptime(deb, "%Y%m%d")
end = dt.strptime(fin, "%Y%m%d") + timedelta(days=1)

def hour_range(start, end):
    while start < end:
        yield start
        start += timedelta(hours=1)

date_list = [h.strftime('%Y/%m/%d %H') for h in hour_range(start, end)]

```