TidyHTMLTreeBuilder won't import

[Magnus Runesson]

When I am importing TidyHTMLTreeBuilding according to http://effbot.org/zone/element-tidylib.htm it complains that elementtree not found.The package python-elementtree is installed.

$ python
Python 2.5.1 (r251:54863, Oct 5 2007, 13:36:32)
[GCC 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from elementtidy import TidyHTMLTreeBuilder
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.5/site-packages/elementtidy/TidyHTMLTreeBuilder.py", line 49, in <module>
    from elementtree import ElementTree
ImportError: No module named elementtree
>>>

I got this problem in Ubuntu 7.10 (Gutsy Gibbon)