$ cat foo/Net/LocalCfg.pm
#!/usr/bin/env perl
use 5.034;
package Net::LocalCfg;

BEGIN { say qq{## Loaded my LocalCfg}; }

sub requires_firewall {
  my( $class ) = shift;

  say STDERR qq{## LocalCfg requires_firewall '$_[0]'};

  return (rand() < 0.5) ? 1 : 0;
}

1;

__END__
$ perl -I ./foo -MNet::Config -E 'say Net::Config->requires_firewall( q{google.com} )'
## Loaded my LocalCfg
0
$ perl -I ./foo -MNet::Config -E 'say Net::LocalCfg->requires_firewall( q{google.com} )'
## Loaded my LocalCfg
## LocalCfg requires_firewall 'google.com'
0