I'm trying to add an argument called 'flags' and do something with the the flag that's entered in the command line depending on what's entered, however the program isn't doing anything with the flag that's entered.

The input needs to be in the format: `program.py -flag`.

```
import argparse

parser = argparse.ArgumentParser()

parser.add_argument('-avgtime', '-avgtemp', '-maxtime', '-maxtemp',
                        nargs='?', dest='flags')
    args = parser.parse_args()

    if args.flags is not None:
        if args.flags == '-avgtime':
            # print something
        elif args.flags == '-avgtemp':
            # print something
        elif args.flags == '-maxtime':
            # print something
        elif args.flags == '-maxtemp':
            # pint something
    else:
        print "Command Not Executed"

```

When I enter the command `python program.py -avgtime` it just prints the "Command Not Executed" statement because the args.flags Namespace is null.