Merge pull request #18 from xiangli-cmu/master

combine testandset and set command
fix typos
Merge pull request #20 from ccding/dev

fix typos
use function fatal(...)
Merge pull request #21 from ccding/dev

use function fatal(...)
clean code
Merge pull request #22 from ccding/devc

clean code
remove trailing space
clean format with gofmt -w
Merge pull request #23 from ccding/devd

remove trailing space