Already unicode.
```python
> /edx/app/edxapp/edx-platform/common/lib/xmodule/xmodule/lti_module.py(347)context_id()
    346         import ipdb; ipdb.set_trace()
--> 347         return self.course_id
    348 

ipdb> type(self.course_id)
<type 'unicode'>
ipdb> 
```