Bite 56. Add a command line interface to our BMI calculator

Complete create_parser below so that our BMI program can be called like this:

$ python bmi.py -h
usage: bmi.py [-h] -w WEIGHT -l LENGTH

Calculate your BMI.

optional arguments:
  -h, --help            show this help message and exit
  -w WEIGHT, --weight WEIGHT
                        Your weight in kg
  -l LENGTH, --length LENGTH
                        Your length in cm

$ python bmi.py -w 80 -l 187
Your BMI is: 22.88

Please note that calc_bmi and handle_args are given, you only need to code create_parser!

We have two more Bites to practice argparse: 57 and 58.