def test_sibling(self):
        """
        L{URL.sibling} of a L{URL} replaces the last path segment, but does not
        affect the query or fragment.
        """
        urlpath = URL.fromText(theurl)
        self.assertEqual(
            "http://www.foo.com/a/nice/path/sister?zot=23&zut",
            urlpath.sibling(u'sister').asText()
        )
        # Use an url without trailing '/' to check child removal.
        theurl2 = "http://www.foo.com/a/nice/path?zot=23&zut"
        urlpath = URL.fromText(theurl2)
        self.assertEqual(
            "http://www.foo.com/a/nice/sister?zot=23&zut",
            urlpath.sibling(u'sister').asText()
        )

        L{URL.sibling} of a L{URL} replaces the last path segment, but does not
        affect the query or fragment.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/python/test/test_url.py