So, you add a command to your debugger that lets you step over a "block" (a sequence of statements surrounded by braces -- the analog to Lisp's PROGN and Scheme

So, you add a command to your debugger that lets you step over a "block" (a sequence of statements surrounded by braces -- the analog to Lisp's PROGN and Scheme's BEGIN) and before you debug the undifferentiated stream of many statements, you factor it into a handful of statements -- without introducing any new function names -- some of which are blocks.