https://docs.python.org/3.5/whatsnew/3.5.html#pep-448-additional-unpacking-generalizations https://www.python.org/dev/peps/pep-0448
https://docs.python.org/3.5/whatsnew/3.5.html#pep-448-additional-unpacking-generalizations
https://www.python.org/dev/peps/pep-0448