$a, $b, $c = 1, 2, 3;

    the order of evaluation is
          (((( $a ), $b ), $c = 1 ), 2), 3)

    so...
    1) $a gets evaluated
    2) $b gets evaluated
    3) $c = 1 gets evaluated
    4) 2 gets evaluated
    5) 3 gets evaluated
    6) return 3