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

python-txlongpoll is installed in your system.

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

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

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

python-txlongpoll package basic information: