anchor.diff:          #{ Ref := #value{type=Type} } -> Type;
           #{} -> none
       end;
  -get_raw_type(Src, #vst{}) ->
  +get_raw_type(Src, #vst{current=#st{}}) ->
       get_literal_type(Src).
   
   get_literal_type(nil) -> 
  
positive.code: 
  vi_safe(return, Vst) ->
      assert_durable_term({x,0}, Vst),
      verify_return(Vst),
      kill_state(Vst);
  
  %%
  %% Matching and test instructions.
  
negative.code:     verify_y_init(Vst0),
      Vst = deallocate(Vst0),
      verify_call_args(Name, Live, Vst),
      verify_return(Vst).
  
  verify_call_args(_, 0, #vst{}) ->
      ok;
  