def leading_expv(self):
        if self:
            return self.ring.leading_expv(self)
        else:
            return None
Confirm a default control-port is set if not user-supplied.
dataset/ETHPy150Open sympy/sympy/sympy/polys/rings.py/PolyElement.leading_expv--crossover with--dataset/ETHPy150Open meejah/txtorcon/test/test_torconfig.py/LaunchTorTests.test_tor_connection_default_control_port