ReferenceError: fetch is not defined

I am trying to get random image; however, I got the error message.

*Code*

```
image().then(result => {
    console.log(result);
});
```

*Error*

```
ReferenceError: fetch is not defined
    at Object.exports.image (/srv/node_modules/rangen/dist/image.js:13:5)
```