anchor.diff:                  true ->
                       case rand:uniform(10) rem 2 =:= 0 of 
                           true ->
  -                            [{set,{var,0},{call,?FAULT_MODEL,resolve_all_faults_with_heal,[]}}];
  +                            [{set,{var,0},{call,fault_model(),resolve_all_faults_with_heal,[]}}];
                           false ->
  -                            [{set,{var,0},{call,?FAULT_MODEL,resolve_all_faults_with_crash,[]}}]
  +                            [{set,{var,0},{call,fault_model(),resolve_all_faults_with_crash,[]}}]
                       end;
                   false ->
  -                    [{set,{var,0},{call,?FAULT_MODEL,resolve_all_faults_with_heal,[]}}]
  +                    [{set,{var,0},{call,fault_model(),resolve_all_faults_with_heal,[]}}]
               end,
   
               %% Only global node commands.
               CommandsWithOnlyGlobalNodeCommands = lists:map(fun(Fun) ->
  -                {set,{var,0},{call,?SYSTEM_MODEL,Fun,[]}}
  +                {set,{var,0},{call,system_model(),Fun,[]}}
               end, node_global_functions()), 
   
               %% Derive final command sequence.
  
positive.code:         Other ->
              list_to_atom(Other)
      end.
  
negative.code: 
              %% Only global node commands.
              CommandsWithOnlyGlobalNodeCommands = lists:map(fun(Fun) ->
                  {set,{var,0},{call,system_model(),Fun,[]}}
              end, node_global_functions()), 
  
              %% Derive final command sequence.
              FinalCommands0 = case os:getenv("IMPLEMENTATION_MODULE", "false") of
                  "paxoid" ->
                      [
  