sub Main {
    my @dirs = DirsForDonuts( '.../paths.txt' );
    for my $dir( @dirs ){
        DonutXmlChildren( $dir );
    }
} ## end sub Main

sub DirsForDonuts {
    my( $dirfile ) = @_;
    my @dirs = path( $dirfile )->lines_utf8;
    s/\s+$// for @dirs; ## no trailing whitespace
    return @dirs;
} ## end sub DirsForDonuts

sub DonutXmlChildren {
    my( $directory , $date, $bak ) = @_;
    $date   ||= POSIX::strftime( '%Y-%m-%d', localtime );
    $bak    ||= "$date.bak";
    my @xml_files = XmlChildren( $directory );
    for my $file ( @xml_files ) {
        Donut( $file, "$file-$bak" );
    }
} ## end sub DonutXmlChildren

sub XmlChildren {
    return path( shift )->children( qr/\.xml$/ );
} ## end sub XmlChildren