code: def drop_cache(self):
          '''
          Drops all changes in the cache.
          '''
          del self._cache
          self._cache  = {}
          del self._wqueue
          self._wqueue = set()
          self._cur_size = f drop_cache(self):
          '''
          Drops all changes in the cache.
          '''
          del self._cache
          self._cache  = {}
          del self._wqueue
          self._wqueue = set()
          self._cur_size = 0
docs: Drops all changes in the cache.