anchor.diff:          {no,F1,St1} ->                          %Not expanded
               try
                   lfe_eval:expr(F1, Env),
  -                {Env,St1}
  +                {['progn'],Env,St1}             %Ignore the value
               catch
                   _:_ ->
  -                    {Env,add_error({bad_env_form,expression}, St1)}
  +                    {['progn'],Env,add_error({bad_env_form,expression}, St1)}
               end
       end.
   
  
positive.code:     end;
  function_arity(_) -> no.
  
  %% pass_eval_set(Args, Env, State) -> {Env,State}.
  %%  Evaluate the set form.
  
  pass_eval_set(Args, Env, St) ->
  
negative.code: 
  pass_eval_set_1(Pat, Guard, Exp, Env0, St) ->
      Val = lfe_eval:expr(Exp, Env0),
      {yes,_,Bs} = lfe_eval:match_when(Pat, Val, Guard, Env0),
      Env1 = foldl(fun ({N,V}, E) -> add_vbinding(N, V, E) end, Env0, Bs),
      Sets = [ [set,N,V] || {N,V} <- Bs ],
      {['progn'|Sets],Env1,St}.
  
  %% pass_expand_expr(Expr, Env, State, ExpandFlag) ->
  %%     {yes,Exp,State} | {no,State}.
  