* Sort events at start, as otherwise we risk misidentifying the last event
* Keep inserted events in the correct order, ensuring we don't misidentify the last event
- e.g. network conditions mean that 'live' events come in non-sequentially
- or so that adding custom events to an existing event works
* Ensure we maintain original ordering while inserting a new event which has an identical timestamp to an existing event. This came up with a series of mutations which had the same timestamp but needed to be applied in the correct order
* Fast track the common case of a new event being added which occurs after all prior events
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