--- collect! {|item| ..}
--- map! {|item| ..}

    Ǥ֤˥֥åϤɾη̤Ǥ
    ֤ޤEnumerable#collect [Enumerable/collect] ⻲ȡ

    self ֤ޤ

    :
        ary = [1, 2, 3]
        ary.map! {|i| i * 3 }
        p ary   #=> [3, 6, 9]

