code: def increment(self, key, cache=None, amount=1):
          
          if cache is None:
              cache = self.name
          if cache is None:
              raise ValueError("Cache name must be set")
          cache = quote_plus(cache)
          key = quote_plus(key)
  
          body = json.dumps({"amount": amount})
  
          result = self.client.post("caches/%s/items/%s/increment" % (cache,
              key), body, {"Content-Type": "application/json"})
          result = result["body"]
          return Item(values=result, cache=cache, key=key)
docs: Query the server to increment the value of the key by the specified
          amount. Negative amounts can be used to decrement.
  
          Keyword arguments:
          key -- the key the item is stored under. Required.
          cache -- the cache the item belongs to. Defaults to None, which uses
                   self.name. If no name is set, raises a ValueError.
          amount -- the amount to increment the value by. Can be negative to
                    decrement the value. Defaults to 1.