'Show that a user can retrieve any user\'s public keys.'

def test_keys(self):

    cassette_name = self.cassette_name('keys')
    with self.recorder.use_cassette(cassette_name):
        user = self.gh.user('sigmavirus24')
        keys = list(user.keys())
    assert (len(keys) > 0)
    for key in keys:
        assert isinstance(key, github3.users.Key)
