what does the @ in python do
The most common use for an `@` symbol in Python is to denote a decorator for a class or function. Decorators can be used to apply transformations to classes or functions.

Another use for the `@` symbol in Python, more commonly seen in code working with mathematical operations, is for matrix multiplication. In this context, `x @ y` is equivalent to `x.__matmul__(y)`.

If you would like me to elaborate on one or both of these contexts, feel free to ask.
how can I do a program in python that supports calling it like `python foo.py --arg 2` and prints `2`