Assignment operators work as in C. That is,

        $a += 2;

    is equivalent to

        $a = $a + 2;

    although without duplicating any side effects that
    dereferencing the lvalue might trigger

##</code><code>##

    $baseball{yankees} = $baseball{yankees} . $baseball{mets};

##</code><code>##

    $baseball{yankees} .= $baseball{mets}