sub rand
{
    my ($self, $N) = @_;

    unless (ref $self) {
        Math::Random::MT::srand() unless defined $gen;
        $self = $gen;
    }

    return $self->genrand();
}

sub irand
{
    my ($self, $N) = @_;

    unless (ref $self) {
        $N = $self;
        Math::Random::MT::srand() unless defined $gen;
        $self = $gen;
    }

    return ($N || 1) * $self->genirand();
}