--- indexes(key_1, ... , key_n)
--- indices(key_1, ... , key_n)

    ǻꤵ줿֤ͤޤ

    ruby 1.8 feature:
    Υ᥽åɤ version 1.8 Ǥϡobsolete Ǥ
    Ѥȷٹåɽޤ
     Hash#values_at [Hash/values_at] Ѥޤ

