It's not easy to convert this to the new syntax.
One close solution would be:
:start;
repeat
:step1;
:step2;
:step3;
repeat while (successful?) -> false
-> true;
repeat
:step4;
:step5;
repeat while (successful?) -> false
:step6;
stop
But that's not exactly your example.
The difficulty is that the new activity beta syntax is close to usual C/Java/C#/VB/Python/C++ language.
Implementing your example (especially the link back to step3 ) with those languages is not that easy, because it breaks execution flow.