human
Here's a good function header given the following:
I wrote the below code

    out = u'<a    href="%(url)s"    rel="nofollow">%(url)s</a>'
    tests = (('http://\xc3\xa9x\xc3\xa1mpl\xc3\xa9.com/', (out % {'url': u'http://\xe9x\xe1mpl\xe9.com/'})), ('http://\xc3\xa9x\xc3\xa1mpl\xc3\xa9.com/\xc3\xad\xc3\xa0\xc3\xb1\xc3\xa1/', (out % {'url': u'http://\xe9x\xe1mpl\xe9.com/\xed\xe0\xf1\xe1/'})), ('http://\xc3\xa9x\xc3\xa1mpl\xc3\xa9.com/\xc3\xad\xc3\xa0\xc3\xb1\xc3\xa1/?foo=bar', (out % {'url': u'http://\xe9x\xe1mpl\xe9.com/\xed\xe0\xf1\xe1/?foo=bar'})), ('http://\xc3\xa9x\xc3\xa1mpl\xc3\xa9.com/\xc3\xad\xc3\xa0\xc3\xb1\xc3\xa1/?f\xc3\xb3o=b\xc3\xa1r', (out % {'url': u'http://\xe9x\xe1mpl\xe9.com/\xed\xe0\xf1\xe1/?f\xf3o=b\xe1r'})))
    def check(test, expected_output):
        eq_(expected_output, linkify(test))
    for (test, expected_output) in tests:
        (yield (check, test, expected_output))

What's a good function header?
assistant
#Here's a good function header.

def test_url_utf8():