def METHOD_NAME(self) -> None:
    req = HostRequestMock()
    self.assertIsNone(get_browser_language_code(req))
    req = HostRequestMock()
    req.META["HTTP_ACCEPT_LANGUAGE"] = "de"
    self.assertEqual(get_browser_language_code(req), "de")
    req = HostRequestMock()
    req.META["HTTP_ACCEPT_LANGUAGE"] = "en-GB,en;q=0.8"
    self.assertEqual(get_browser_language_code(req), "en-gb")
    # Case when unsupported language has higher weight.
    req = HostRequestMock()
    req.META["HTTP_ACCEPT_LANGUAGE"] = "en-IND;q=0.9,de;q=0.8"
    self.assertEqual(get_browser_language_code(req), "de")
    # Browser locale is set to unsupported language.
    req = HostRequestMock()
    req.META["HTTP_ACCEPT_LANGUAGE"] = "en-IND"
    self.assertIsNone(get_browser_language_code(req))
    req = HostRequestMock()
    req.META["HTTP_ACCEPT_LANGUAGE"] = "*"
    self.assertIsNone(get_browser_language_code(req))