Accepts a yaml file containing a list of regions as an argument and does stuff with each.

region.py

#!/usr/bin/env python

import argparse, yaml


def region(regiondict):
    for i in regiondict:
        print(i)


def main():
    parser = argparse.ArgumentParser(description='Do stuff with this region')
    parser.add_argument('-r', '--region', help='Yaml file containing a bunch of regions')
    args = parser.parse_args()
    region_file = open(args.region, 'r')
    region_dict = yaml.safe_load(region_file)
    region(region_dict['region'])


if __name__ == "__main__":
    main()

region_list.yml

region:
    - us-east-1
    - us-west-2