python 초 단위 loop

from datetime import date, timedelta, time, datetime

start_date = date(2021, 1, 1)
start_time=time(0,0,0)
end_date = date(2021, 1, 1)
end_time=time(1,0,0)
start = datetime.combine(start_date, start_time)
end = datetime.combine(end_date, end_time)
delta = timedelta(minutes=1)
while start <= end:
    print (start.strftime("%Y-%m-%d %H:%M:%S"))
    start += delta