everything it does, but most importantly for this document, it
produces a mapping of "symbolic_locals" which maintains a mapping from
the frameâs "f_locals" to TorchDynamo internal Variable objects (more
on these in a moment. "symbolic_locals" is filled via traversing the
frameâs locals:
self.symbolic_locals = collections.OrderedDict(
       (k, VariableBuilder(self, LocalSource(k))(f_locals[k]))
       for k in vars
       if k in f_locals
   )
The important component here  is the invocation of a call into
"VariableBuilder". "VariableBuilder"âs call implementation proxies
into a function called "_wrap", which in turn both constructs
instances of "VariableTracker" and calls "make_guards" on them. More
on that later.
This mapping, in turn, is critical as each Variable has associated
guards, which are then passed to "self.output", the instance of
"OutputGraph", an fx tracer, mentioned in 4.2 of the section above. If
you recall, this "OutputGraph", stored in a variable called "output"