sub d :lvalue {
   print("$_[0]: ", defined($_[1]) ? "[$_[1]]" : "undef", "\n");
   $_[1]
}

our $fred = 78;
d("pre local", $fred);
d("post local", local $fred);

##</code><code>##

pre local: [78]
post local: undef

##</code><code>##

sub d :lvalue {
   print("$_[0]: ", defined($_[1]) ? "[$_[1]]" : "undef", "\n");
   $_[1]
}

our $fred = 78;
d("pre local", $fred);
d("post assign", d("post local", local $fred) = 90);

##</code><code>##

pre local: [78]
post local: undef
post assign: [90]