$ sudo apt-get update
$ sudo apt-get install postgres-xc-plpython 

postgres-xc-plpython is installed in your system.

Make ensure the postgres-xc-plpython package were installed using the commands given below,

$ sudo dpkg-query -l | grep postgres-xc-plpython *

You will get with postgres-xc-plpython package name, version, architecture and description in a table

postgres-xc-plpython package basic information: