Nope, there are three different options:
- annotations (parse `@Xxxx`)
- types (pare `str: string`)
- type assertion (produce `assert.xxx`)

In the case of `--types=true --annotations=true --type-assertions=false`, Traceur does generate:
```js
sum.parameters = [[assert.number], [assert.number]];
```
(Btw, I think it should generate this type metadata even if `--types=true --annotations=false` as this is not annotation, but rather exposing the type information in runtime; this can be used for other meta programing, not just runtime type assertion; for instance I use it in my Dependency Injection system to figure out what to inject)

In this case, there is no `assert.number` defined and I don't wanna import the assert library. So I suggest, if we wanna use the lowercase "types" (`boolean`, `number`, `string`), we should have it defined in Traceur runtime.