Date array generator

dategen.py

from datetime import date, datetime, timedelta
from calendar import monthrange
import pytz
dateRange = []

curTime = datetime.now()

def generateRange(start,end):
    for y in range(start,end):
        for m in range(1,13):
            datestr = '{}-{}-{}'.format(y,m,monthrange(y, m)[1])
            dateformat = datetime.strptime(datestr, "%Y-%m-%d")
            if dateformat < curTime:
                dateRange.append(datestr)

generateRange(2020,2021)
print(dateRange)