You don't need this source code unless you want to modify the package. If you just want to use the Postmaster Python bindings, you should run:
easy_install postmaster
See http://www.pip-installer.org/en/latest/index.html for instructions on installing pip. If you are on a system with easy_install but not pip, you can use easy_install instead. If you're not using virtualenv, you may have to prefix those commands with +sudo+. You can learn more about virtualenv at http://www.virtualenv.org/
To install from source, run:
python setup.py install
Please see https://www.postmaster.io/docs for the most up-to-date documentation.