<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def flush(self):
 """ Remove all items from the cache. """

        if os.path.isdir(self._directory):
            for root, dirs, files in os.walk(self._directory, topdown=False):
                for name in files:
                    os.remove(os.path.join(root, name))

                for name in dirs:
                    os.rmdir(os.path.join(root, name))