Well spotted, although I think that the issue is the indent of the return statement  The return statement should be un-indented by one level because at present it only processes the first cookie.

e.g.

``` python
>>> def add(cookies):
...     if isinstance(cookies, list):
...         for cookie in cookies:
...             for key, value in cookie.items():
...                 print '%s: %s' % (key, value)
...             return
...
>>> add([
...     {'a': 'a1', 'b': 'b1'},
...     {'c': 'c1', 'd': 'd1'},
... ])
a: a1
b: b1
>>>
```

However as you said, this is an issue across a few of the drivers which would probably best be fixed with a single pull request :smile: