def add_policy(self, policy):
        if isinstance(policy, RelayPolicy):
            self.relay_policies.append(policy)
        else:
            raise TypeError('Argument not a RelayPolicy.')
Adds a |RelayPolicy| to be executed each time the relay attempts
dataset/ETHPy150Open slimta/python-slimta/slimta/relay/__init__.py/Relay.add_policy