How to set verbosity level based on command line flag

argparse_verbose.py

import argparse
import logging

logging.basicConfig()
logger = logging.getLogger()

parser = argparse.ArgumentParser()
parser.add_argument("-v", "--verbose", const = 1, default = 0,type = int, nargs="?",
                    help="increase verbosity: 0 = only warnings, 1 = info, 2 = debug. No number means info. Default is no verbosity.")

args = parser.parse_args()

if args.verbose == 0:
    logger.setLevel(logging.WARN) 
elif args.verbose == 1:
    logger.setLevel(logging.INFO) 
elif args.verbose == 2:
    logger.setLevel(logging.DEBUG)