This means you can't pass in a result path as a sequence of strings, which seems a shame
  - i.e. I can say "self.assertArrayEqual(a, 'testing/array_1')" but not "self.assertArrayEqual(a, ('testing','array_1'))" as you might expect/hope.
This is also reflected in the usages in test_transport, where they all call get_result_path anyway.  So you could reasonably either fix this, or remove it ('b' must be a full path).