Fix by adding comment when executing make test that send
"FAIL: test/test_distance.py:6 | E0611 no-name-in-module:  No name 'assert_raises' in module 'nose.tools'"
See http://blog.daniel-watkins.co.uk/2013/09/fixing-nosetools-pylint-errors.html
I choose to comment to ignore the E0611 error or more refactoring using unittest would have been required
e.g https://stackoverflow.com/questions/10716506/where-is-noses-assert-raises-function