Create prog.py

Example from the documentation.

* https://docs.python.org/dev/library/argparse.html

>>> prog.py --help
usage: prog.py [-h]

Process some integers.

optional arguments:
  -h, --help  show this help message and exit


>>> prog.py -
usage: prog.py [-h]
prog.py: error: unrecognized arguments: -


>>> prog.py 1
usage: prog.py [-h]
prog.py: error: unrecognized arguments: 1


>>> prog.py 1 2 3
usage: prog.py [-h]
prog.py: error: unrecognized arguments: 1 2 3