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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def store(self, key, expiry, data):
 """ Add a result to the cache :key: Cache key to use :expiry: The expiry timestamp after which the result is stale :data: The data to cache """

        self.cache.set(key, (expiry, data), self.cache_ttl)

        if getattr(settings, 'CACHEBACK_VERIFY_CACHE_WRITE', True):
            # We verify that the item was cached correctly.  This is to avoid a
            # Memcache problem where some values aren't cached correctly
            # without warning.
            __, cached_data = self.cache.get(key, (None, None))
            if data is not None and cached_data is None:
                raise RuntimeError(
                    "Unable to save data of type %s to cache" % (
                        type(data)))