my $dd_new = $cls->can("dedupe_$dd") //
die "unsupported dedupe strategy: $dd\n";
bless [ $dd_new->() ], $cls; # [ $skv, $cb ]
my $dd_new = $cls->can("dedupe_$dd") //
die "unsupported dedupe strategy: $dd\n";
bless [ $dd_new->() ], $cls; # [ $skv, $cb ]