code: def namedb_genesis_block_history_hash(genesis_block_history):
      
      # no-whitespace sorted serialization
      preimage = json.dumps(genesis_block_history, sort_keys=True, separators=(',',':'))
      h = hashlib.sha256(preimage).hexdigest()
      return h
docs: Make a "fake" txid for the genesis block history
      Returns a 32-byte hash (single sha256), hex-encoded
      (single sha256 so it can be easily verified against our genesis block tooling)