Hi @domchen, I'm your friendly neighborhood Microsoft Pull Request Bot (You can call me MSBOT). Thanks for your contribution!

This seems like a small (but important) contribution, so no Contribution License Agreement is required at this point. Real humans will now evaluate your PR.

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The continuous integration check seems failed. But I built it and tested it successfully on my computer, which part did I do wrong?

it's lint error. Please fix code style in checker

All checks have passed now, Thanks for the tip~ @HerringtonDarkholme

thanks @domchen. looks good. can you please add a unit test to tests\cases\compiler.

@mhegazy The unit test is added. I am not familiar with this, is the style of the unit test ok?

Please accept-baseline. For guidance please read this https://github.com/Microsoft/TypeScript/blob/master/CONTRIBUTING.md#adding-a-test

Finally! I will know the drill next time. Thanks again for your help. @HerringtonDarkholme

Thanks @domchen and @HerringtonDarkholme!