How to use the bugsnag.middleware.MiddlewareStack function in bugsnag

def test_order_of_middleware(self):

        a = []

        m = MiddlewareStack()

        m.before_notify(lambda _: a.append(1))
        m.before_notify(lambda _: a.append(2))

        m.after_notify(lambda _: a.append(4))
        m.after_notify(lambda _: a.append(3))

        m.run(None, lambda: None)

        self.assertEqual(a, [1, 2, 3, 4])

def test_insert_before_default_ordering(self):
        a = []

        m = MiddlewareStack()
        m.append(TestMiddlewareClassA)
        m.append(TestMiddlewareClassB)
        m.insert_before(TestMiddlewareClass, TestMiddlewareClassC)
        m.run(a, lambda: a.append('Callback'))

        self.assertEqual(a, ['A', 'B', 'C', 'Callback'])

def test_before_notify_returning_false(self):

        a = []

        m = MiddlewareStack()

        m.before_notify(lambda _: False)
        m.before_notify(lambda _: a.append(1))

        m.run(None, lambda: a.append(2))

        self.assertEqual(a, [])

def test_after_exception_handling(self):
        a = []

        m = MiddlewareStack()
        m.after_notify(lambda _: a.penned(1))
        m.run(None, lambda: a.append(2))

        self.assertEqual(a, [2])

def test_insert_before_ordering(self):
        a = []

        m = MiddlewareStack()
        m.append(TestMiddlewareClassA)
        m.append(TestMiddlewareClassB)
        m.insert_before(TestMiddlewareClassA, TestMiddlewareClassC)
        m.run(a, lambda: a.append('Callback'))

        self.assertEqual(a, ['C', 'A', 'B', 'Callback'])

def test_before_exception_handling(self):

        a = []

        m = MiddlewareStack()
        m.before_notify(lambda _: a.penned(1))
        m.run(None, lambda: a.append(2))

        self.assertEqual(a, [2])

def test_insert_after_ordering(self):
        a = []

        m = MiddlewareStack()
        m.append(TestMiddlewareClassA)
        m.append(TestMiddlewareClassB)
        m.insert_after(TestMiddlewareClassA, TestMiddlewareClassC)
        m.run(a, lambda: a.append('Callback'))

        self.assertEqual(a, ['A', 'C', 'B', 'Callback'])

def test_insert_after_default_ordering(self):
        a = []

        m = MiddlewareStack()
        m.append(TestMiddlewareClassA)
        m.append(TestMiddlewareClassB)
        m.insert_after(TestMiddlewareClass, TestMiddlewareClassC)
        m.run(a, lambda: a.append('Callback'))

        self.assertEqual(a, ['A', 'B', 'C', 'Callback'])

self.lib_root = get_python_lib()
        self.project_root = os.getcwd()
        self.app_version = None
        self.params_filters = ["password", "password_confirmation", "cookie",
                               "authorization"]
        self.ignore_classes = [
            "KeyboardInterrupt",
            "django.http.Http404",
            "django.http.response.Http404",
        ]
        self.endpoint = "https://notify.bugsnag.com"
        self.session_endpoint = "https://sessions.bugsnag.com"
        self.auto_capture_sessions = False
        self.traceback_exclude_modules = []

        self.middleware = MiddlewareStack()

        self.internal_middleware = MiddlewareStack()
        self.internal_middleware.append(DefaultMiddleware)
        self.internal_middleware.append(SessionMiddleware)

        self.proxy_host = None

        if not os.getenv("DYNO"):
            self.hostname = socket.gethostname()
        else:
            self.hostname = None

        self.runtime_versions = {"python": platform.python_version()}

self.app_version = None
        self.params_filters = ["password", "password_confirmation", "cookie",
                               "authorization"]
        self.ignore_classes = [
            "KeyboardInterrupt",
            "django.http.Http404",
            "django.http.response.Http404",
        ]
        self.endpoint = "https://notify.bugsnag.com"
        self.session_endpoint = "https://sessions.bugsnag.com"
        self.auto_capture_sessions = False
        self.traceback_exclude_modules = []

        self.middleware = MiddlewareStack()

        self.internal_middleware = MiddlewareStack()
        self.internal_middleware.append(DefaultMiddleware)
        self.internal_middleware.append(SessionMiddleware)

        self.proxy_host = None

        if not os.getenv("DYNO"):
            self.hostname = socket.gethostname()
        else:
            self.hostname = None

        self.runtime_versions = {"python": platform.python_version()}