What does it mean when you specify two APIs?
This is what the documentation says:

```
  --api API             API type/version pairs, like "gl=3.2,gles=", no
                        version means latest
```

But I'm not sure what it means. Is it an intersection or union of APIs?

I'm making an app that supports GL3.3 and GLES3.0, and I was hoping that might help me adhere to the common set of features of both.

Cheers!