$ sudo apt-get update
$ sudo apt-get install python-zope.viewlet 

python-zope.viewlet is installed in your system.

Make ensure the python-zope.viewlet package were installed using the commands given below,

$ sudo dpkg-query -l | grep python-zope.viewlet *

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

python-zope.viewlet package basic information: