anchor.diff:                             erl_syntax:tuple([erl_syntax:atom(call),
   					     erl_syntax:variable("_"),
   					     erl_syntax:abstract(Fun),
  -					     erl_syntax:list([erl_syntax:variable("_") || _<-lists:seq(1,Args)])])],[],
  +					     erl_syntax:list([erl_syntax:variable("_") || _<-lists:seq(1,Args + 1)])])],[],
                             [erl_syntax:atom(true) ]) ||
           {_Mod,Fun,Args} <- Calls ])] ++
     % initial_state_data
  
positive.code:   % next_state_data
    [ erl_syntax:function(
        erl_syntax:atom(next_state_data),
        [ erl_syntax:clause([erl_syntax:variable("_From"),erl_syntax:variable("_To"),erl_syntax:variable("S"),
                             erl_syntax:variable("_V"),
                             erl_syntax:tuple([erl_syntax:atom(call),
                                              erl_syntax:variable("_"),
                                              erl_syntax:abstract(Fun),
                                              erl_syntax:list([erl_syntax:variable("_") || _<-lists:seq(1,Args)])])],[],
                            [erl_syntax:variable("S") ])  || {_Mod,Fun,Args} <- Calls ])]++
    % postconditions
    [ erl_syntax:function(
        erl_syntax:atom(postcondition),
  
negative.code:                            erl_syntax:tuple([erl_syntax:atom(call),
                                              erl_syntax:variable("_"),
                                              erl_syntax:abstract(Fun),
                                              erl_syntax:list([erl_syntax:variable("_") || _<-lists:seq(1,Args + 1)])]),
                             erl_syntax:variable("R")],[],
                            [erl_syntax:case_expr(
                               erl_syntax:variable("R"),[
  