anchor.diff:      log_details(Det, Halt),
       Context#context{active = ?SETS:new(), blocked = ?SETS:new()};
   
  -%% Is_process_alive message handler.
   handler(is_process_alive, Lid, #context{details = Det} = Context, TargetPid) ->
       TargetLid = lid:from_pid(TargetPid),
       log_details(Det, {is_process_alive, Lid, TargetLid}),
       Context;
   
  -%% Link message handler.
   handler(link, Lid, #context{details = Det} = Context, TargetPid) ->
       TargetLid = lid:from_pid(TargetPid),
       log_details(Det, {link, Lid, TargetLid}),
       Context;
   
  -%% Monitor message handler.
   handler(monitor, Lid, #context{details = Det} = Context, {Item, _Ref}) ->
       TargetLid = lid:from_pid(Item),
       log_details(Det, {monitor, Lid, TargetLid}),
       Context;
   
  -%% Process_flag message handler.
   handler(process_flag, Lid, #context{details = Det} = Context, {Flag, Value}) ->
       log_details(Det, {process_flag, Lid, Flag, Value}),
       Context;
  
positive.code:     log_details(Det, {'receive_no_instr', Lid, Msg}),
      Context;
  
  %% Register message handler.
  handler(register, Lid, #context{details = Det} = Context, {RegName, RegLid}) ->
      log_details(Det, {register, Lid, RegName, RegLid}),
      Context;
  
  %% Send message handler.
  handler(send, Lid, #context{details = Det} = Context, {DstPid, Msg}) ->
      DstLid = lid:from_pid(DstPid),
      log_details(Det, {send, Lid, DstLid, Msg}),
      Context;
  
  %% Spawn message handler.
  %% First, link the newly spawned process to the scheduler process.
  %% The new process yields as soon as it gets spawned and the parent process
  %% yields as soon as it spawns. Therefore wait for two `yield` messages using
  %% two calls to the dispatcher.
  handler(spawn, ParentLid,
  	#context{active = Active, details = Det} = Context, ChildPid) ->
      link(ChildPid),
  
negative.code: 	    Context#context{active = NewActive, error = Error}
      end;
  
  %% Return empty active and blocked queues to force run termination.
  handler(halt, Lid, #context{details = Det} = Context, Misc) ->
      Halt =
  