anchor.diff:                  (SysEvs =:= []) ->
                       Error;
                   true ->
  -                    throw({skip, {system_events, SysEvs}})
  +                    skip({system_events, SysEvs})
               end;
   
   
  
positive.code: 	    case Ret of
  		{error, Reason} ->
  		    exit(Reason);
  		{skip, _} = SKIP ->
  		    exit(SKIP);
  		OK ->
  		    OK
  	    end
  
negative.code:                 (SysEvs =:= []) ->
                      Error;
                  true ->
                      skip({system_events, SysEvs})
              end;
  
  
  