reorganize ex 1.6.8 into correct example and WYSS subsections, extend examples
reorganize ex 1.6.8 into correct example and WYSS subsections, extend examples

LispTO/llthw,LispTO/llthw,LispTO/llthw,tang-junjie/llthw,tang-junjie/llthw,tang-junjie/llthw