--- captures      ruby 1.8 feature

    $1, $2, ... Ǽ
    ֤ޤto_a Ȱۤʤ $& 
    Ǥ˴ޤߤޤ󡣥롼פ˥ޥåʬʸ󤬤ʤб
    Ǥ nil ˤʤޤ

        /(foo)(bar)(BAZ)?/ =~ "foobarbaz"
        p $~.to_a       # => ["foobar", "foo", "bar", nil]
        p $~.captures       # => ["foo", "bar", nil]

