anchor.diff:  %% @see num_calls/3
   %% @see num_calls/4
   -spec history(Mod::atom(), Pid:: pid() | '_') -> history().
  -history(Mod, Pid) when is_atom(Mod), is_pid(Pid) orelse Pid == '_' -> 
  +history(Mod, Pid) when is_atom(Mod), is_pid(Pid) orelse Pid == '_' ->
       match_history(match_mfa('_', Pid), call(Mod, history)).
   
   %% @spec unload() -> list(atom())
  
positive.code:                Arity::pos_integer(), Sequence::[term()]) -> ok.
  sequence(Mod, Func, Arity, Sequence)
    when is_atom(Mod), is_atom(Func), is_integer(Arity), Arity >= 0 ->
      call(Mod, {sequence, Func, Arity, Sequence});
  sequence(Mod, Func, Arity, Sequence) when is_list(Mod) ->
      lists:foreach(fun(M) -> sequence(M, Func, Arity, Sequence) end, Mod),
      ok.
  
negative.code: handle_call({expect, FuncAri, Clauses}, _From, S) ->
      NewExpects = store_expect(S#state.mod, FuncAri,
                                Clauses,
                                S#state.expects),
      {reply, ok, S#state{expects = NewExpects}};
  handle_call({delete, Func, Arity}, _From, S) ->
  