of a simple case. To understand this functionality better, read the
other functions on "GuardBuilder", or better yet, dump the "code"
variable in "compile_check_fn" to see what is getting produced,
especially on larger, real models.
Summary
In this section, we have reviewed:


The role of ".valid" and invalidation around weak references (and
  potentially soon to be NN Moduleinvalidations).


How the C++ side of guard functions ("checktype_id",
  "_check_tensors", etc) operate


What happens when guards fail.


What happens if we produce invalid guard code.


We covered how user provided code wrapped in a TorchDynamo context
goes on to get traced and tracked internally, organized into
"VariableTracker"s "Source"s and subsequently "Guard"s, and how those
"Guards" in turn guide cache entry selection and invalidation when
handing Python code.