# babel-check-duplicated-nodes

Duplicated AST nodes often lead to obscure bugs. This module checks your AST and
throws a helpful error if you include a duplicated node in your output. It's
useful when authoring babel transforms.

This piece of code was originally written by @nicolo-ribaudo and is included in
[babel's codebase](https://github.com/babel/babel/blob/d383659ca6adec54b6054f77cdaa16da88e8a171/packages/babel-helper-transform-fixture-test-runner/src/index.js#L128).

## API

```js
checkDuplicatedNodes(babel, ast)
```