use Scalar::Util "weaken";
use vars qw(%STORE);


sub new {
   my ($class,$key) = @_;
   return $STORE{$key} if exists $STORE{$key} && defined $STORE{$key};
   my $obj = $class->retrieve($key);
   weaken $obj;
   $STORE{$key} = $obj;
   return $obj;
}

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