my $diff= easy( \@a, \@b );
    while(  @$diff  ) {
        my( $same, $aMin, $aMax, $bMin, $bMax )=
            splice @$diff, 0, 5;
        $_++   for  $aMin, $aMax, $bMin, $bMax;
        next   if  $same;
        my $sep= '';
        if(  $bMax < $bMin  ) {
            print "$aMin,$aMax","d$bMax\n";
        } elsif(  $aMax < $aMin  ) {
            print "$aMax","a$bMin,$bMax\n";
        } else {
            $sep= "---\n";
            print "$aMin,$aMax","c$bMin,$bMax\n";
        }
        for(  @a[$aMin-1..$aMax-1]  ) {
            print "< $_";
        }
        print $sep;
        for(  @b[$bMin-1..$bMax-1]  ) {
            print "> $_";
        }
    }