pipdeptree is a command line utility for displaying the python
packages installed in an environment in form of a dependency
tree. Since 'pip freeze' shows all dependencies as a flat list,
finding out which are the top level packages and which packages do
they depend on requires some effort. This utility tries to solve this
problem.

Note: All required deps are build only deps.

#2.16.2 is the last version compatible with the version of packaging
included with 15.0.
