Formatter function dependencies not included

When function passed to formatter calls other functions (i.e. lodash or any other library) or functions defined outside of the scope of formatter function, it throws `Can't find variable` exception. This seems to be due to outer functions or libraries don't make it to the WebView where charts are rendered. How can we bypass it?
Example of not working formatter funtion:
```javascript
const sum = (a, b) => a + b;

function formatter() {
return sum(this.value, 1);
}
```
will throw `Can't find variable sum`