_redef();
    sub _redef {
        my $parent = shift || '::';
        for my $ns (grep /^\w+::/, keys %{$parent}) {
            $ns = $parent . $ns;
            _redef($ns) unless $ns eq '::main::';
            for my $sub (keys %redef) {
                *{$ns . $sub} = $redef{$sub} if (exists ${$ns}{$sub});
            }
        }
    }