[gihub][fun] collapsible markdown

https://gist.github.com/joyrexus/16041f2426450e73f5df9391f7f7ae5f

--

## collapsible markdown?

<details><summary>CLICK ME</summary>

<p> 

#### yes, even hidden code blocks!  

```python print("hello world!") ``` 

</p> 

</details>

--