This patchset helps clean up the code and docs:

* Fix redundant parenthesese.
* Fix mismatching params in func return.
* Fix variable name collides with imported package name and builtin
  function or reserved words.
* Fix word typos.

Change-Id: I30304c233067ead7e74d18e3caf2604b3ed1490a
Signed-off-by: Baohua Yang <yangbaohua@gmail.com>