def delete(self, session_key=None):
        self._session_key = ''
        self._session_cache = {}
        self.modified = True
determines the (start, end) region under the given header
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/Django-1.6.10/django/contrib/sessions/backends/signed_cookies.py/SessionStore.delete--crossover with--dataset/ETHPy150Open mgaitan/sublime-rst-completion/headers.py/RstHeaderTree.region