This is because the post was originally written as a Jupyter notebook [1] and exported as markdown. These notebooks allow you to mix markdown and code which is

This is because the post was originally written as a Jupyter notebook [1] and exported as markdown. These notebooks allow you to mix markdown and code which is executed interactively, and use `!` as a special syntax to denote bash commands instead of Python statements. [1]: https://jupyter.org/ https://jupyter.org/