def dec(self, key, delta=1):
        value = (self.get(key) or 0) - delta
        return value if self.set(key, value) else None
Decrements the value of a key by `delta`.  If the key does
dataset/ETHPy150Open GoogleCloudPlatform/appengine-flask-skeleton/lib/werkzeug/contrib/cache.py/BaseCache.dec