If *key* is in the dictionary, remove it and return its value,
        else return *default*. If *default* is not given and *key* is not in
        the dictionary, a KeyError is raised.

def pop(self, key, default=NONE):
        """
        If *key* is in the dictionary, remove it and return its value,
        else return *default*. If *default* is not given and *key* is not in
        the dictionary, a KeyError is raised.
        """
        if key in self:
            self._list_remove(key)
            return self._pop(key)
        else:
            if default is NONE:
                raise KeyError(key)
            else:
                return default