def ensure_vistrail(self, locator):
        raise NotImplementedError("Subclass must implement ensure_vistrail")
Test XML rendering.
dataset/ETHPy150Open VisTrails/VisTrails/vistrails/core/application.py/VistrailsApplicationInterface.ensure_vistrail--crossover with--dataset/ETHPy150Open jpadilla/django-rest-framework-xml/tests/test_renderers.py/XMLRendererTestCase.test_render_float