def get_many(self, keys, version=None):
        d = {}
        for k in keys:
            val = self.get(k, version=version)
            if val is not None:
                d[k] = val
        return d
Fetch a bunch of keys from the cache. For certain backends (memcached,
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/core/cache/backends/base.py/BaseCache.get_many