def test_serializedAttributeWithRenderable(self):
        """
        Like L{test_serializedAttributeWithTransparentTag}, but when the
        attribute is a provider of L{IRenderable} rather than a transparent
        tag.
        """
        @implementer(IRenderable)
        class Arbitrary(object):
            def __init__(self, value):
                self.value = value
            def render(self, request):
                return self.value
        self.checkAttributeSanitization(Arbitrary, passthru)

        Like L{test_serializedAttributeWithTransparentTag}, but when the
        attribute is a provider of L{IRenderable} rather than a transparent
        tag.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_flatten.py