Code review comment for lp:~caravone/txstatsd/statsd-timings-consistency

One thing I wasn't sure about was the expected behavior of the increment/decrement calls. As you can see from the unit tests, the basic Metrics object emits deltas for each increment/decrements, while the ExtendedMetrics version keeps a cumulative delta and emits that. Not sure if it's a bug or just a subtlety of the API.