DefaultAccessController = async () => {
  // An AccessController may do any async initialization stuff here...
  return {
    canAppend: async (entry) => true
  }
}
@module Log
@description
Log is a verifiable, append-only log CRDT.

Implemented as a Merkle-CRDT as per the paper
["Merkle-CRDTs: Merkle-DAGs meet CRDTs"]{@link https://arxiv.org/abs/2004.00107}