def test_getHeaderReceivedMultiples(self):
        """
        When there are multiple values for a single request header,
        L{http.Request.getHeader} returns the last value.
        """
        req = http.Request(DummyChannel(), False)
        req.requestHeaders.setRawHeaders(b"test", [b"lemur", b"panda"])
        self.assertEqual(req.getHeader(b"test"), b"panda")

        When there are multiple values for a single request header,
        L{http.Request.getHeader} returns the last value.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/web/test/test_http.py