def test_type(self):
        rset = event.ResultSet()
        with pytest.raises(NotImplementedError):
            rset.extend([])
        with pytest.raises(NotImplementedError):
            rset.extend(False)
def _getN(self, n):
        n -= 1
        p = self.head
        while n:
            p = p.next
            n -= 1
        return p