anchor.diff:  -endif.
   -ifdef(BUILTIN).
   
  --type mypid_plain() :: erl_pid_plain().
   %% @doc BUILTIN: Returns the pid of the current process.
   -spec this() -> pid().
   this() ->
  
positive.code: -endif.
  -ifdef(SIMULATION).
  
  -type mypid_plain() :: erl_pid_plain().
  %% @doc SIMULATION: Returns the pid of the current process.
  -spec this() -> pid().
  this() ->
  
negative.code: 
  -ifdef(TCP_LAYER).
  
  %% @doc TCP_LAYER: Returns the pid of the current process.
  -spec this() -> mypid_plain().
  this() ->
  