#! perl
# .perldb
my $code = q{
    if (${^GLOBAL_PHASE} eq 'INIT') {
        unshift @DB::typeahead, 'n';
    } else {
        my $code = q{%s};
        $code = sprintf $code, $code;
        @$DB::pre = grep $_ ne $code, @$DB::pre;
    }
};
unshift @$DB::pre, sprintf $code, $code;