Take code annotations into account

I noticed that for code with annotations the annotations are not taken into account when creating the dependency graph.

As an example, for 
```
def do_stuff(config: Config, model: MyModel):
    model.apply_config(config)
    return model.eval()
```
`do_stuff` is marked as being independent of `Config` and `MyModel`, as it does not call `Config` and `MyModel` class explicitly in the body.