## Functions

Functions are defined by an optional list of parameters in parentheses, an arrow, and the function body. The empty function looks like this: `->`

```
codeFor('functions', 'cube(5)')
```

Functions may also have default values for arguments, which will be used if the incoming argument is missing (`null` or `undefined`).

```
codeFor('default_args', 'fill("cup")')
```
