anchor.diff:  set_and_get_test(Ctx) -> [
       ?_assertEqual(ok, ephp_context:set(Ctx,{variable,<<"a">>,[]},10)),
       ?_assertEqual(ok, ephp_context:set(Ctx,{variable,<<"b">>,[]},20)),
  +    ?_assertEqual(ok, ephp_context:set(Ctx,{variable,<<"c">>,[]},undefined)),
  +    ?_assertEqual(ok, ephp_context:set(Ctx,{variable,<<"d">>,[]},true)),
  +    ?_assertEqual(ok, ephp_context:set(Ctx,{variable,<<"e">>,[]},false)),
  +
       ?_assertEqual(10, ephp_context:get(Ctx,{variable,<<"a">>,[]})),
  -    ?_assertEqual(20, ephp_context:get(Ctx,{variable,<<"b">>,[]}))
  +    ?_assertEqual(20, ephp_context:get(Ctx,{variable,<<"b">>,[]})),
  +    ?_assertEqual(undefined, ephp_context:get(Ctx,{variable,<<"c">>,[]})),
  +    ?_assertEqual(true, ephp_context:get(Ctx,{variable,<<"d">>,[]})),
  +    ?_assertEqual(false, ephp_context:get(Ctx,{variable,<<"e">>,[]}))
   ].
   
   set_and_get_array_test(Ctx) -> [
  
positive.code:     ?_assertEqual(30, ephp_context:get(Ctx,{variable,<<"a">>,[{text,<<"hola">>}]})),
      ?_assertEqual(40, ephp_context:get(Ctx,{variable,<<"a">>,[{int,2},{int,0}]}))
  ].
  
negative.code:         fun start/0,
          fun stop/1, [
          fun set_and_get_test/1,
          fun set_and_get_array_test/1,
          fun resolve_assign/1,
          fun operation_test/1,
          fun arith_mono_test/1
      ]}.
  
  start() ->
  