Is this scrub?

可以带block了，不过结果好像有些不一样..
```
3] pry(main)> "abc\u3042\xE3\x80".scrub{|bytes| '<'+bytes.unpack('H*')[0]+'>' }
=> "abcあ<e3><80>"
[4] pry(main)> "abc\u3042\x81".scrub("*")
=> "abcあ*"
[5] pry(main)> "abc\u3042\x81".scrub
=> "abcあ"
```