## Experiment

Two markdown cells with the same bit of math,
first not using `\newcommand`

, then using it.

```
**Cell A**
We denote by $\operatorname{span}(u, v)$ the span of two vectors $u$ and $v$.
```

```
**Cell B**
$\newcommand{\span}{\operatorname{span}}$
We denote by $\span(u, v)$ the span of two vectors $u$ and $v$.
```