Not sure if httpbin is down or your tests are failing? Use `mock` to stub out your external calls!

mock.py

import mock
import requests
import unittest

def get():
    # Retrieves data from an external service eg. Twitter, Google
    try:
        return requests.get('http://external-service.com/')
    except requests.RequestException:
        return None


class Test(unittest.TestCase):
    def test(self):
        # Ensure `get` handles `RequestException`.
        get_mock = mock.MagicMock()
        get_mock.side_effect = requests.RequestException()

        with mock.patch("requests.get", get_mock):
            self.assertEquals(get(), None)


if __name__ == '__main__':
    unittest.main(verbosity=2)