anchor.diff:  			    E
   		    end
   	    end;
  -	error ->
  +        _ ->
   	    E
       end.
   
  
positive.code: %%  return Expr0 unchanged.
  %%
  case_expand_var(E, #sub{t=Tdb}) ->
      case orddict:find(cerl:var_name(E), Tdb) of
  	{ok,T0} ->
  	    case cerl:is_c_tuple(T0) of
  		false ->
  		    E;
  
negative.code:     {Vs2,As1,Ss} = let_substs_1(Vs1, As0, Sub1),
      Sub2 = sub_add_scope([V || #c_var{name=V} <- Vs2], Sub1),
      {Vs2,As1,
      foldl(fun ({V,S}, Sub) -> sub_set_name(V, S, Sub) end, Sub2, Ss)}.
  
  let_substs_1(Vs, #c_values{es=As}, Sub) ->
      let_subst_list(Vs, As, Sub);
  