$ ./835728.pl
Name "main::module" used only once: possible typo at ./835728.pl line 9.
size=3
Use of uninitialized value $module{"port_list"} in array dereference at ./835728.pl line 9.
Use of uninitialized value $module{"port_list"} in concatenation (.) or string at ./835728.pl line 9.
size=