def rec_update(self, other, **third):
try:<EOL><INDENT>iterator = other.iteritems()<EOL><DEDENT>except AttributeError:<EOL><INDENT>iterator = other<EOL><DEDENT>self.iter_rec_update(iterator)<EOL>self.iter_rec_update(third.iteritems())<EOL>
Recursively update the dictionary with the contents of other and
        third like dict.update() does - but don't overwrite sub-dictionaries.
        Example:
        >>> d = RecursiveDictionary({'foo': {'bar': 42}})
        >>> d.rec_update({'foo': {'baz': 36}})
        >>> d
        {'foo': {'baz': 36, 'bar': 42}}