The canonical solution in the standard library is argparse (docs):
Here is an example:
from argparse import ArgumentParser 
parser = ArgumentParser() 
parser.add_argument("-f", "--file", dest="filename", help="write report to FILE", metavar="FILE") 
parser.add_argument("-q", "--quiet", action="store_false", dest="verbose", default=True, help="don't print status messages to stdout") 
args = parser.parse_args()
argparse supports (among other things):