anchor.diff:  
   %% What node-specific operations should be called.
   node_commands() ->
  -    [{call, ?MODULE, write, [node_name(), key(), value()]},
  -     {call, ?MODULE, read, [node_name(), key()]}].
  +    [{call, ?MODULE, write, [primary_node_name(), key(), value()]},
  +     {call, ?MODULE, read, [primary_node_name(), key()]}].
   
   %% Assertion commands.
   node_assertion_functions() ->
  
positive.code:     NodeState.
  
  %% Postconditions for node commands.
  node_postcondition(_NodeState, {call, ?MODULE, read, [_Node, _Key]}, {error, not_primary}) ->
      true;
  node_postcondition(#node_state{store=Store}, {call, ?MODULE, read, [Node, Key]}, {ok, Value}) ->
      case dict:find(Key, Store) of
          {ok, Value} ->
  
negative.code: value() ->
      oneof([1, 2, 3]).
  
  primary_node_name() ->
      oneof([hd(names())]).
  
  node_name() ->
      oneof(names()).
  
  