Fixes #3529 -- more explicit documentation about Context.update. Thanks for the patch, ggetzie.

        super(Context, self).__init__(dict_)

    def update(self, other_dict):

        "Like dict.update(). Pushes an entire dictionary's keys and values onto the context."

        "Pushes other_dict to the stack of dictionaries in the Context"

        if not hasattr(other_dict, '__getitem__'):

            raise TypeError('other_dict must be a mapping (dictionary-like) object.')

        self.dicts.append(other_dict)

    ...

    django.template.ContextPopException

In addition to ``push()`` and ``pop()``, the ``Context``

object also defines an ``update()`` method. This works like ``push()``

but takes a dictionary as an argument and pushes that dictionary onto

the stack instead of an empty one.

    >>> c = Context()

    >>> c['foo'] = 'first level'

    >>> c.update({'foo': 'updated'})

    {'foo': 'updated'}

    >>> c['foo']

    'updated'

    >>> c.pop()

    {'foo': 'updated'}

    >>> c['foo']

    'first level'

Using a ``Context`` as a stack comes in handy in some custom template tags, as

you'll see below.