Python: accept multiple instances of a command line argument

multi_option.py

"""
Copyright 2016 David Antliff; this file is licensed under the terms of the Apache license version 2.0. For a full copy of the license, see https://www.apache.org/licenses/LICENSE-2.0

Accept two styles of repeated options on the command line.

Style 1 - each instance repeats the option itself. E.g.

  $ python prog --option A --option B

Style 2 - each instance occurs after a single instance of the option. E.g.

  $ python prog --option C D E

This solution combines both styles. E.g.

  $ python ./test_argparse.py --option A --option B --option C D E
  ['A', 'B', 'C', 'D', 'E']

"""
import argparse

parser = argparse.ArgumentParser()
parser.add_argument("--option", nargs="+", action="append", dest="options")
args = parser.parse_args()

# args.options will be a list of lists, so flatten with:
options = [item for sublist in args.options for item in sublist]
print options