And when generating statement for `LetStatement`, it should be indented like this,
```js
let (variable = ...)
    statement;
```
And when `BlockStatement` is used, it should be indented like this,
```js
let (variable = ...) {
   ...
}
```

I think `WithStatement` rule may help you to follow this formatting.
https://github.com/Constellation/escodegen/blob/master/escodegen.js#L1919