More ast parsing clean-up.
More ast parsing clean-up.

hugovk/coveragepy,hugovk/coveragepy,blueyed/coveragepy,hugovk/coveragepy,hugovk/coveragepy,hugovk/coveragepy,nedbat/coveragepy,blueyed/coveragepy,nedbat/coveragepy,nedbat/coveragepy,blueyed/coveragepy,blueyed/coveragepy,nedbat/coveragepy,nedbat/coveragepy,blueyed/coveragepy