Added default value for default kwargs for QueryDict.

    Returns ``True`` if the given key is set. This lets you do, e.g., ``if "foo"

    in request.GET``.

.. method:: QueryDict.get(key, default)

.. method:: QueryDict.get(key, default=None)

    Uses the same logic as ``__getitem__()`` above, with a hook for returning a

    default value if the key doesn't exist.

.. method:: QueryDict.setdefault(key, default)

.. method:: QueryDict.setdefault(key, default=None)

    Just like the standard dictionary ``setdefault()`` method, except it uses

    ``__setitem__()`` internally.

    Returns a copy of the object, using ``copy.deepcopy()`` from the Python

    standard library. This copy will be mutable even if the original was not.

.. method:: QueryDict.getlist(key, default)

.. method:: QueryDict.getlist(key, default=None)

    Returns the data with the requested key, as a Python list. Returns an

    empty list if the key doesn't exist and no default value was provided.

    Appends an item to the internal list associated with key.

.. method:: QueryDict.setlistdefault(key, default_list)

.. method:: QueryDict.setlistdefault(key, default_list=None)

    Just like ``setdefault``, except it takes a list of values instead of a

    single value.