Call me crazy but this would look better if it were simply:

```python
if self._content_consumed:
    chunks = iter_slices(self._content, chunk_size)
else:
    chunks = generate()
```

Ternaries are not used in the requests code base and are generally advised against by PEP8 (one of the few places requests' style and PEP8 happen to coincide). You're also unconditionally creating two iterators which incurs the cost of creation and garbage collection (which has two parts: decrementing the ref count and collecting the object on the next sweep of the garbage collector) as opposed to creating one iterator (and binding) and returning it.