my @set;
sub contains { @set{$_[0]}; }
sub add { @set{$_[0]} = 1; }

##</code><code>##

my @set;
sub contains { $set[$_[0]]; }
sub add { $set[$_[0]] = 1; }

##</code><code>##

my $set = "";
sub contains { vec($set, $_[0], 1); }
sub add { vec($set, $_[0], 1) = 1; }

##</code><code>##

$set{@elements} = ();