Chapter 7. Working with Nodes, Page 154

Location on the page: 
code example
Chapter: 
7. Working with Nodes
Error: 

the fields are not collapsed automatically. With drupal 6.8, I can find no file named "collapsible.js" in the distribution. At http://www.drupalbook.com/node/137, there is mention that the collapsing Javascript is included automatically only in forms, but even adding form tags to the page does not seem to make the collapsability thing work.

Did I miss something about turning on JS includes?

Description of the Error: 

[The file that contains the JS is at misc/collapse.js. Drupal's fieldsets are collapsible by default. -JV]