...
sub load_cache {
	my( $source, $dest ) = @_;

	my $data = do {;
		if( defined $source ) {
			unless( -e $source ) {
				carp "Net::Mac::Vendor cache source [$source] does not exist";
				return;
				}

			do { local( @ARGV, $/ ) = $source; <> }
			}
		else {
			__PACKAGE__->ua->get( oui_url() )->res->body;
			}
		};
...