Removing 'Overwriting Variables' from the 'In This Chapter' list.
Merge pull request #26 from alfredocarella/master

Translated "es_chapter4.txt"->"capítulo4.txt"
id. update glossary
id-chapter4
Merge pull request #27 from bbn-bernard/master

id-chapter4
Merge branch 'master' of github.com:asweigart/inventwithpython3rded
Another round of copyeditting for Chapter 9
Another round of edits for Chapter 9.5