$ sudo apt-get update
$ sudo apt-get install python-libxml2 

python-libxml2 is installed in your system.

Make ensure the python-libxml2 package were installed using the commands given below,

$ sudo dpkg-query -l | grep python-libxml2 *

You will get with python-libxml2 package name, version, architecture and description in a table

python-libxml2 package basic information: