Use default hash method to return hash value of a piece of Python
        picklable object.

def of_pyobj(self, pyobj):
        """Use default hash method to return hash value of a piece of Python
        picklable object.
        """
        m = self.hash_algo()
        m.update(pickle.dumps(pyobj, protocol=self.pk_protocol))
        if self.return_int:
            return int(m.hexdigest(), 16)
        else:
            return m.hexdigest()