anchor.diff:      Vst;
   
   %% Other test instructions.
  +valfun_4({test,is_atom,{f,Lbl},[Src]}, Vst) ->
  +    assert_term(Src, Vst),
  +    set_aliased_type({atom,[]}, Src, branch_state(Lbl, Vst));
  +valfun_4({test,is_boolean,{f,Lbl},[Src]}, Vst) ->
  +    assert_term(Src, Vst),
  +    set_aliased_type(bool, Src, branch_state(Lbl, Vst));
   valfun_4({test,is_float,{f,Lbl},[Float]}, Vst) ->
       assert_term(Float, Vst),
       set_type({float,[]}, Float, branch_state(Lbl, Vst));
  
positive.code: 	 valid=0 :: non_neg_integer(),		%Valid slots
  	 slots=0 :: non_neg_integer()		%Number of slots
  	}).
  
  validate_1(Is, Name, Arity, Entry, Ft) ->
      validate_2(labels(Is), Name, Arity, Entry, Ft).
  
negative.code:     Type0 = get_term_type(Tuple, Vst),
      Type = upgrade_tuple_type({tuple,[0]}, Type0),
      set_aliased_type(Type, Tuple, branch_state(Lbl, Vst));
  valfun_4({test,is_integer,{f,Lbl},[Src]}, Vst) ->
      assert_term(Src, Vst),
      set_aliased_type({integer,[]}, Src, branch_state(Lbl, Vst));
  valfun_4({test,is_nonempty_list,{f,Lbl},[Cons]}, Vst) ->
      assert_term(Cons, Vst),
      Type = cons,
  