anchor.diff:      NewActive = ?SETS:add_element(ChildLid, Active),
       Context#context{active = NewActive};
   
  -%% Spawn_opt message handler.
   %% Similar to above depending on options.
   handler(spawn_opt, ParentLid,
   	#context{active = Active, details = Det} = Context, {Ret, Opt}) ->
  
positive.code:     NewActive = ?SETS:add_element(ChildLid, Active),
      Context#context{active = NewActive};
  
  %% Unlink message handler.
  handler(unlink, Lid, #context{details = Det} = Context, TargetPid) ->
      TargetLid = lid:from_pid(TargetPid),
      log_details(Det, {unlink, Lid, TargetLid}),
      Context;
  
  %% Unregister message handler.
  handler(unregister, Lid, #context{details = Det} = Context, RegName) ->
      log_details(Det, {unregister, Lid, RegName}),
      Context;
  
  %% Whereis message handler.
  handler(whereis, Lid, #context{details = Det} = Context, {RegName, Result}) ->
      ResultLid = lid:from_pid(Result),
      log_details(Det, {whereis, Lid, RegName, ResultLid}),
  
negative.code:     NewActive = ?SETS:add_element(ChildLid, Active),
      Context#context{active = NewActive};
  
  %% FIXME: Refactor this (it's exactly the same as 'spawn')
  handler(spawn_link, ParentLid,
  	#context{active = Active, details = Det} = Context, ChildPid) ->
      link(ChildPid),
  