big app in python

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i am trying to convince my nephew to learn python.   he's been asking some things about python and we came to this point.  what is the biggest, or a very big, application program (but not a web app) that is written in python?  this would be something that its user starts, but infrequently quits, as opposed to a command line shell command (because it exits frequently).  he's wondering how well python manages memory in long running programs.

edit:

i think he wants to see an app that is doing a GUI interface with the user and not a server thing (and not something doing client/server although it can use a DB).