code: def parse_args():
      
      parser = argparse.ArgumentParser()
      parser.add_argument('-M', action='store_true')
      parser.add_argument('-m', action='store_true')
      parser.add_argument('-f', action='store_true')
      args = parser.parse_args()
      major, minor, fix = args.M, args.m, args.f
      if major + minor + fix != 1:
          fail('Please select one and only one action.')
      return major, minor, fix
docs: Parse the args, returns if the type of update:
      Major, minor, fix