anchor.diff:  -spec read_write_test() -> boolean().
   read_write_test() ->
       proper:quickcheck(prop_read_write(), [{to_file, user}, {numtests, 1000}]).
  +
  +-spec short_test() -> boolean().
  +short_test() ->
  +    proper:quickcheck(prop_short(), [{to_file, user}, {numtests, 1000}]).
   
   -spec int_deref_test() -> boolean().
   int_deref_test() ->
  
positive.code: -module(nifty_lib_test).
  -export([cstr_list_test/0,
  	 read_write_test/0,
  	 int_deref_test/0]).
  
  -include_lib("proper/include/proper.hrl").
  
negative.code: -type mystring() :: [1..255].
  -type byte() :: 0..255.
  
  
  %% auxilary functions
  -spec cstr_list_comp(mystring()) -> boolean().
  cstr_list_comp(Str) ->
      CStr = nifty:list_to_cstr(Str),
      DStr = nifty:dereference(CStr),
      ok = nifty:free(CStr),
      DStr =:= Str.
  
  short_comp(Sh) ->
      P = nifty:pointer_of(Sh, "unsigned short"),
      DSh = nifty:dereference(P),
      ok = nifty:free(P),
      Sh =:= DSh.
  
  -spec write_read([byte()]) -> boolean().
  write_read(Data) ->
      Ptr = nifty:mem_write(Data),
      DData = nifty:mem_read(Ptr, length(Data)),
      ok = nifty:free(Ptr),
      DData =:= Data.
  
  %% properties
  -spec prop_cstr_list() -> proper:outer_test().
  