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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def delete(self, session_key=None):
 """ Deletes the current session, or the one specified in ``session_key``. :keyword str session_key: Optionally, override the session key to delete. """


        if session_key is None:
            if self.session_key is None:
                return
            session_key = self.session_key

        self.table.delete_item(Key={'session_key': session_key})