anchor.diff:  
   
   %%%%%%%%%%%%%%%% access of learner entry
  --spec learner_key(entry())      -> any().
  -learner_key(Entry)              -> element(1, Entry).
  --spec learner_datatype(entry()) -> crdt:crdt_module().
  -learner_datatype(Entry)         -> element(2, Entry).
   -spec learner_learnt(entry())   -> crdt:crdt().
   learner_learnt(Entry)           -> element(3, Entry).
   
  
positive.code:     ok.
  
  %%%%%%%%%%%%%%%%%% access of proposer entry
  -spec entry_key(entry())            -> any().
  entry_key(Entry)                    -> element(1, Entry).
  -spec entry_datatype(entry())       -> crdt:crdt_module().
  entry_datatype(Entry)               -> element(2, Entry).
  -spec entry_clients(entry())       -> [any()].
  
negative.code: entry_propval(Entry)                -> element(8, Entry).
  -spec entry_bufval(entry())        -> crdt:crdt().
  entry_bufval(Entry)                -> element(9, Entry).
  
  entry_add_client(Entry, Client) ->
      Clients = element(3, Entry),
  