code: def make_snapshot_from_ops_hash( cls, record_root_hash, prev_consensus_hashes ):
          
          # mix into previous consensus hashes...
          all_hashes = prev_consensus_hashes[:] + [record_root_hash]
          all_hashes.sort()
          all_hashes_merkle_tree = MerkleTree( all_hashes )
          root_hash = all_hashes_merkle_tree.root()
  
          consensus_hash = StateEngine.calculate_consensus_hash( root_hash )
          return consensus_hash
docs: Generate the consensus hash from the hash over the current ops, and 
          all previous required consensus hashes.