--- next
--- next!
--- succ
--- succ!

    ʲΤ褦((**))ʸ֤ޤ

      "aa".succ => "ab"
      "99".succ => "100"
      "a9".succ => "b0"
      "Az".succ => "Ba"
      "zz".succ => "aaa"

    succ!, next! ʸƤ˲Ū˽ޤ

