We now enforce the following rules:
1. No duplicate topics or data.
2. Topics must have 32 byte keys.
3. Topics may not be skipped. (e.g., no t1 & t3 without a t2).
4. Raw codecs.
We _don't_ require that topics/data be emitted in any specific order.
We _skip_ events with unknown keys. We _drop_ events that violate the
above rules.
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