def clear(self):
        raise NotImplementedError('subclasses of BaseCache must provide a clear() method')
Normalize and convert all keys to BlobKey type.
dataset/ETHPy150Open django/django/django/core/cache/backends/base.py/BaseCache.clear--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/blobstore/blobstore.py/BlobInfo.__normalize_and_convert_keys