Code review中+1 -1 +0 -0的由来

这是python风格的code review用词，在PEP 0010上提出。
http://www.python.org/dev/peps/pep-0010/

+1 I like it

+0 I don't care, but go ahead

-0 I don't care, so why bother?

-1 I hate it