How can we use resumeToPDF?

This might be a bit silly, but I couldn't figure out how to use this module! 
I tried:

```
resumeToPDF("resume.json", function function_name(pdf) {
  fs.writeFile("a.pdf", pdf, function(err) {
    if(err) {
        console.log(err);
    } else {
        console.log("resume was saved!");
    }
  });
});
```

with no luck, would really appreciate any examples.
