Binary package “python3-traceback2” in ubuntu xenial

backports of the traceback module - Python 3.x

 This package offers a backport of the traceback package to older supported
 Pythons. Users would typically do: "import traceback2 as traceback" then use
 the module as if it was the system traceback.
 .
 In Python 2.x, unlike traceback, traceback2 creates unicode output (because it
 depends on the linecache2 module).
 .
 This package contains the Python 3.x module.